2x plus y equals 7-y equals x plus 1?

Answer 1

2x + y = 7

y = x + 1

This is a simple linear system of equations, to solve it re-order and eliminate terms to solve for a single and then substitute back into the main equation

rewrite y = x + 1 as x - y = -1

eliminate y

(2x + y = 7) + (x - y = -1) = (3x = 6)

from this x = 2, plugging back into the first equation produces y = 3

Answer 2

-4(2x+7y)use x=4 and y=7