Solve the system by either elimation or substitution:
x+8y=18
y=-2/7x-18/7
Putting the y in (substitution)..
x + 8(-2/7x-18/7)=18
x-16/7x-144/7=18
These fractions get ridiculous so I'm sure you can work it out from there. Get rid of the -144/7 by adding 144/7 to the right side. Then do x-16/7x. Then solve.