We have a system of two linear equations with two variables, $x$ and $y$: $20x + 30y = 210$ $80x + 50y = 490$ We want to find the values of $x$ and $y$ that satisfy both equations.

AlgebraLinear EquationsSystems of EquationsSolving Equations
2025/4/3

1. Problem Description

We have a system of two linear equations with two variables, xx and yy:
20x+30y=21020x + 30y = 210
80x+50y=49080x + 50y = 490
We want to find the values of xx and yy that satisfy both equations.

2. Solution Steps

First, simplify the first equation by dividing by 10:
20x+30y=21020x + 30y = 210
2x+3y=212x + 3y = 21 (Equation 1)
Also, simplify the second equation by dividing by 10:
80x+50y=49080x + 50y = 490
8x+5y=498x + 5y = 49 (Equation 2)
Now, we want to eliminate one of the variables. Let's eliminate xx. Multiply Equation 1 by -4:
4(2x+3y)=4(21)-4(2x + 3y) = -4(21)
8x12y=84-8x - 12y = -84 (Equation 3)
Add Equation 3 to Equation 2:
(8x+5y)+(8x12y)=49+(84)(8x + 5y) + (-8x - 12y) = 49 + (-84)
8x+5y8x12y=49848x + 5y - 8x - 12y = 49 - 84
7y=35-7y = -35
Divide both sides by -7:
y=357y = \frac{-35}{-7}
y=5y = 5
Now, substitute y=5y = 5 into Equation 1:
2x+3(5)=212x + 3(5) = 21
2x+15=212x + 15 = 21
2x=21152x = 21 - 15
2x=62x = 6
x=62x = \frac{6}{2}
x=3x = 3

3. Final Answer

x=3x = 3 and y=5y = 5