Math Problem Statement

Use elimination method to determine the values of x and y in the simultaneous equations below x + y = 27 x / 30 + y / 24 = 1

Solution

We can solve the given system of equations using the elimination method. The equations are:

  1. x+y=27x + y = 27
  2. x30+y24=1\frac{x}{30} + \frac{y}{24} = 1

Step 1: Simplify the second equation

Multiply through by the least common multiple (LCM) of 30 and 24, which is 120, to eliminate the fractions:

120x30+120y24=1201120 \cdot \frac{x}{30} + 120 \cdot \frac{y}{24} = 120 \cdot 1

This simplifies to:

4x + 5y = 120 \tag{2'}

Now we have the system:

  1. x+y=27x + y = 27
  2. 4x+5y=1204x + 5y = 120

Step 2: Eliminate one variable

From the first equation, solve for yy in terms of xx:

y=27xy = 27 - x

Substitute y=27xy = 27 - x into the second equation 4x+5y=1204x + 5y = 120:

4x+5(27x)=1204x + 5(27 - x) = 120

Step 3: Simplify and solve for xx

Expand and simplify:

4x+1355x=1204x + 135 - 5x = 120

x+135=120-x + 135 = 120

x=15x = 15

Step 4: Solve for yy

Substitute x=15x = 15 into y=27xy = 27 - x:

y=2715=12y = 27 - 15 = 12

Final Answer:

x=15,  y=12x = 15, \; y = 12

Verification:

  • From the first equation: 15+12=2715 + 12 = 27
  • From the second equation: 1530+1224=0.5+0.5=1\frac{15}{30} + \frac{12}{24} = 0.5 + 0.5 = 1

The solution is correct.


Would you like additional explanations or related examples?
Here are 5 related questions for practice:

  1. Solve x+y=20x + y = 20 and x5+y10=3\frac{x}{5} + \frac{y}{10} = 3 using elimination.
  2. Determine the solution to xy=10x - y = 10 and 2x+y=252x + y = 25.
  3. Solve 3x+4y=403x + 4y = 40 and 2xy=102x - y = 10 using elimination.
  4. Use substitution instead of elimination to solve x+y=18x + y = 18 and x6+y9=2\frac{x}{6} + \frac{y}{9} = 2.
  5. Explain how to identify when the elimination method is more efficient than substitution.

Tip: Elimination is particularly useful when one variable can be easily canceled by scaling the equations.

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Math Problem Analysis

Mathematical Concepts

Algebra
Simultaneous Equations
Elimination Method
Fraction Operations

Formulas

x + y = 27
4x + 5y = 120 (derived by multiplying the second equation by the LCM of 30 and 24)

Theorems

Elimination Method for Solving Linear Equations

Suitable Grade Level

Grades 8-10