Question

Solve the simultaneous equations
4x + y = 20
x - y = 15

Answer 1

X=7

y= -8

Explanation:

4x+y+(x-y)=20+15

4x+y+x-y=35

plus y and minus y cancels out.

4x+X= 35

5x=35

X= 7

Substitute X=7 in any equation

x-y=15

7-y=15

y=-8