Math Problem Statement

-2 2/5 × 17/8 and (-3 3/20) × (-1 1/9)

Solution

Let's break down the math problems from the image:

Problem 19:

225×178-2\frac{2}{5} \times \frac{17}{8}

We need to multiply a mixed number and a fraction. First, convert the mixed number into an improper fraction: 225=(2×5)+25=1252\frac{2}{5} = \frac{(2 \times 5) + 2}{5} = \frac{12}{5}

Now the problem becomes: 125×178-\frac{12}{5} \times \frac{17}{8}

Multiply the numerators and the denominators: 12×175×8=20440\frac{-12 \times 17}{5 \times 8} = \frac{-204}{40}

Simplify the fraction: 20440=5110\frac{-204}{40} = \frac{-51}{10}

So, the answer is: 5110-5\frac{1}{10}

Problem 20:

(3320)×(119)\left( -3\frac{3}{20} \right) \times \left( -1\frac{1}{9} \right)

Again, we will convert the mixed numbers to improper fractions.

For 3320-3\frac{3}{20}: 3320=(3×20)+320=63203\frac{3}{20} = \frac{(3 \times 20) + 3}{20} = \frac{63}{20} This is negative, so the fraction is: 6320-\frac{63}{20}

For 119-1\frac{1}{9}: 119=(1×9)+19=1091\frac{1}{9} = \frac{(1 \times 9) + 1}{9} = \frac{10}{9} This is also negative, so the fraction is: 109-\frac{10}{9}

Now multiply the two fractions: 6320×109=63×1020×9=630180-\frac{63}{20} \times -\frac{10}{9} = \frac{63 \times 10}{20 \times 9} = \frac{630}{180}

Simplify the fraction: 630180=72\frac{630}{180} = \frac{7}{2}

So, the answer is: 3123\frac{1}{2}


Would you like further clarification or additional steps for these problems? Feel free to ask!

Here are 5 related questions to deepen your understanding:

  1. How do you simplify improper fractions?
  2. What is the method for multiplying mixed numbers?
  3. How do you simplify a fraction after multiplication?
  4. Can you give examples of adding or subtracting mixed numbers?
  5. What are the differences between multiplying and dividing fractions?

Tip: Always convert mixed numbers into improper fractions before performing any operations.

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Math Problem Analysis

Mathematical Concepts

Multiplying Mixed Numbers
Converting Mixed Numbers to Improper Fractions
Fraction Simplification

Formulas

Mixed number to improper fraction conversion
Multiplication of fractions
Simplifying fractions

Theorems

Fraction multiplication rule
Simplification of fractions

Suitable Grade Level

Grades 6-8