Solve the following equation
2x-y=17
x-y=10

You can isolate y on both sides, getting:
2x-17=y  and    x-10=y

Then, make the two y equal each other, and solve the equation
2x-17=x-10

The answer would be x=7. 
then, plut in the amount into one of the equations:
x-y=10
7-y=10
y=-3
T

Therefore, the answer is x=7 and y = -3, or (7,-3)

This is a system of equations.
1.) Isolate a variable in the equation of your choosing
Ex. x = y +10
2.) Plug in the new equation to the first original one
Ex. 2(y + 10) - y = 17
3.) Solve for the variable in the equation
Step one for this: Distribute 
Ex. 2y +20 - y = 17
Step two for this: Combine like terms
Ex. y +20 = 17
Step three for this: Isolate the variable
Ex. y = -3
4.) Plug in your answer for one variable into one of the original equations
Ex. X - (-3) =10
5.) Solve for x
x + 3 = 10
x = 7
The answer is: x = 7, y = -3

Idk i am in 5th grade lol