5x+3y=10 and x-y=-10

Question

What is x and y? Thanks :)

Answer 1

Elimination method

Given equations are 5x+3y = 10 ---> (1)

x-y = -10

Multiple to each side by 3.

3x-3y = -30 ---> (2)

To eliminate the y value add the equations (1)&(2).

5x+3y = 10

3x-3y = -30

___________

8x = -20

Divide to each side by 8.

8x/8 = -20/8

x = -5/2

Substitute the x value in (1).

5(-5/2)+3y = 10

-25/2+3y = 10

Add 25/2 to each side.

3y = 25/2+10

3y = 45/2

Divide to each side by 3.

y = 45/6

y = 15/2

Solution x = -5/2 and y = 15/2.