Question

what is the solution to the following system
y=1/2x+3
x=15-y

Answer 1

Rearrange either the first equation to solve for x, or the 2nd equation to solve for y. Then sub the rearranged equation into the other, unchanged equation.

Answer 2

You know x = 15 - y, so we can use that in the first equation.
y = 1/2(15 - y) + 3
y = 7.5 - 1/2y +3
y = 10.5 - 1/2y
1.5y = 10.5
y = 7
Now put y = 7 into the second equation.

x = 15 - 7
x = 8
Put x = 8 and y = 7 into both equations and check your answer.

Answer 3

A bit wordy there Blur. Try and let the student do their studying for themselves. They are potentially good enough.