x = 4
y = -5
2x+y = 3(number 1) and 3x-y = 17 (number 2)
Number 1 multiplied by 2 = 4x + 2y = 6 (equation 3)
Number 2 multiplied by 2 = 6x - 2y = 34 (equation 4)
Now we do equation 4 + equation 3. This leaves us with 10x and 0y = 40.
10x =40 so, x= 4.
Now we substitute this into the original equations.
8 + y = 3 and 12 - y =17.
We know that 12 + 5 = 17 and two negatives makes a positive so...
y = -5.
Lets substitute to check:
8 + -5 = 3 (another way of saying 8-5 = 3) and 12 - -5 = 17 (another way of saying 12 + 5 = 17)
Hope this helps :)