Jonas bought 3 books. Each book was the same price. After using a $10-off coupon, the total charge was $20. Which equation can be used to find b, the cost of each book?

maybe showing the graph would

step-by-step explanation:

-387129 iq

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18