Answer:
x=1; y=4
Explanation:
for this system, you could use either substitution or elimination
i'll solve it both ways
SUBSTITUTION:
5x+y=9 becomes y=-5x+9
10x-7y=-18; substitue y from y=-5x+9
10x-7(-5x+9)=-18
10x+35x-63=-18
45x=45
x=1
substitue x into y=-5x+9
y=-5(1)+9
y=4
ELIMINATION
5x+y=9
10x-7y=-18
multiple the top equation by 7 to get 35x+7y=63
now, 7y and -7y cancel out
add the two equations to get 45x=45
x=1
substitute into 5x+y=9
5(1)+y=9
y=4