Answer:
y = (x-7)/9
Step-by-step explanation:
y = 9x + 7
x = 9y + 7
x - 7 = 9y
Multiply the first equation by -1
-3x-y=-4
2x+y=5
Add them up
-x=1
So x=-1
And y=7
So the first option is correct
8 books
5+3=8
