Sasa had some 20-cent and 50-cent coins. Let x be the total number of coins. Then, 7/8 x were 20-cent coins, and the rest, 1 - 7/8 = 1/8 x, were 50-cent coins. After Sasa spent $72.50 worth of 50-cent coins, which is equivalent to 72.50 / 0.50 = 145 50-cent coins, and 5/7 of the 20-cent coins, she had 2/7 x coins left. Find the total amount of money Sasa left.

We are given the following information about Sasa's coins:

1. Let $ x $ be the total number of coins.
2. $ \frac{7}{8}x $ are 20-cent coins.
3. $ \frac{1}{8}x $ are 50-cent coins.
4. After spending 145 50-cent coins and $ \frac{5}{7} $ of the 20-cent coins, she had $ \frac{2}{7}x $ coins left.

We are tasked with finding the total amount of money Sasa has left.

### Step 1: Calculate the number of 50-cent coins Sasa initially had.
The total number of 50-cent coins is $ \frac{1}{8}x $. After spending 145 of these coins, the number of remaining 50-cent coins is:
\[
\frac{1}{8}x - 145
\]

### Step 2: Calculate the number of 20-cent coins Sasa initially had.
The total number of 20-cent coins is $ \frac{7}{8}x $. After spending $ \frac{5}{7} $ of these, the number of remaining 20-cent coins is:
\[
\frac{7}{8}x - \frac{5}{7} \times \frac{7}{8}x = \frac{7}{8}x - \frac{5}{8}x = \frac{2}{8}x = \frac{1}{4}x
\]

### Step 3: Set up the equation for the total number of remaining coins.
After spending some of the coins, Sasa is left with $ \frac{2}{7}x $ coins. This includes the remaining 50-cent and 20-cent coins. Therefore, the equation is:
\[
\left( \frac{1}{8}x - 145 \right) + \frac{1}{4}x = \frac{2}{7}x
\]

### Step 4: Solve the equation.
First, express $ \frac{1}{4}x $ as $ \frac{2}{8}x $, so that all terms have a denominator of 8:
\[
\frac{1}{8}x - 145 + \frac{2}{8}x = \frac{2}{7}x
\]
Combine the terms on the left-hand side:
\[
\frac{3}{8}x - 145 = \frac{2}{7}x
\]
Now, subtract $ \frac{2}{7}x $ from both sides:
\[
\frac{3}{8}x - \frac{2}{7}x = 145
\]
To combine these terms, we need a common denominator. The least common denominator of 8 and 7 is 56. Rewriting the fractions:
\[
\frac{3}{8}x = \frac{21}{56}x, \quad \frac{2}{7}x = \frac{16}{56}x
\]
Thus, the equation becomes:
\[
\frac{21}{56}x - \frac{16}{56}x = 145
\]
\[
\frac{5}{56}x = 145
\]
Solve for $ x $:
\[
x = 145 \times \frac{56}{5} = 1624
\]

### Step 5: Calculate the total amount of money Sasa has left.
Now that we know $ x = 1624 $, we can find how many 50-cent and 20-cent coins Sasa has left.

- The number of remaining 50-cent coins is:
  \[
  \frac{1}{8} \times 1624 - 145 = 203 - 145 = 58
  \]
  The value of the remaining 50-cent coins is:
  \[
  58 \times 0.50 = 29 \text{ dollars}
  \]

- The number of remaining 20-cent coins is:
  \[
  \frac{1}{4} \times 1624 = 406
  \]
  The value of the remaining 20-cent coins is:
  \[
  406 \times 0.20 = 81.20 \text{ dollars}
  \]

Thus, the total amount of money Sasa has left is:
\[
29 + 81.20 = 110.20 \text{ dollars}
\]

### Final Answer:
Sasa has **$110.20** left.

---

Do you need further details or have any questions?

### Related Questions:
1. What would be the result if Sasa had spent half of her 50-cent coins instead of 145?
2. If Sasa had 10 more 20-cent coins initially, what would her remaining total be?
3. How would the result change if Sasa spent $90 worth of 50-cent coins?
4. What if Sasa had only $ \frac{1}{8}x $ coins left instead of $ \frac{2}{7}x $?
5. How can the same problem be solved using a different method, such as substitution?

### Tip:
Always check your work by verifying the total number of remaining coins matches what's expected.

Learn how to solve a coin problem involving 20-cent and 50-cent coins using algebraic equations. This problem walks through key concepts such as fractions, linear equations, and calculating remaining coins. Suitable for students in Grades 8-10.

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