3x + y = 17

4x - y = 18

The two equations given are

3x + y = 17 and 4x - y = 18

Now we will first take one equation

3x + y = 17

Then

y = 17 - 3x

Now replacing the value of y in the second equation we get

4x - y = 18

4x - (17 - 3x) = 18

4x + 3x - 17 = 18

7x = 35

x = 35/7

= 5

Putting the value of x in the first equation we get

3x + y = 17

(3 * 5) + y = 17

15 + y = 17

y = 17 - 15

y = 2

So the value of x is 5 and y is 2

3x+y=17

subtract 3x on both sides

y=17-3x

substitute 17-3x for y in the second equation

4x - (17-3x) = 18

7x-17=18

7x=35

x=5

and now that you know x=5 you can plug that in to either of the original equations

3 (5) + y=17

15+y=17

subtract 15 from both sides

y=2