The Inconsistent Books store changes the normal prices of books on Mondays and Tuesdays. On Monday the price of a book is 10% above the normal price. On Tuesday the price is 10% below the normal price. Sarah bought a book on Monday for $16.50. Would would be the price of that book on a Tuesday?

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

answer: x=3 and y=4

step-by-step explanation: