The sum of two times x and 3 times y is 5. The difference of x and y is 5. Write two equations and graph to find the value of y.

Answer 1

Hello, Eva,

There are two statements that relate x and y:

2x + 3y = 5

and

x - y = 5

Rearrange either so that x is on one side, giving us the equation for what x should be. I'll take the second, since it is the simplest:

x = 5 + y

Use this value of x in the first equation:

2x + 3y = 5

2(5 + y) + 3y = 5

10 + 2y +3y = 5

5y = -5

y = -1

Use y = -1 in either equation to find x:

2x +3(-1) = 5

2x = 8

x = 4

Check the result:

Does the sum of 2(4) + 3(-1) = 5? Yes.

Does the difference of x - y = 5? Yes.

x = 4 and y = -1

I hope this helps,

Bob