Isolate one term (x or y) in one of the equations
6x+6y=0
6x=-6y
X= -1y
Substitute x=-y into the other equation
-7(-y) + 2y =18
7y + 2y =18
9y=18
Y=2
Substitute y=2 into 6x+6y=0
6x + 6(2) = 0
6x + 12=0
6x= -12
X = -2
Answer:
x + y = 20
1.5x + 5y = 54.50
Solve the equations and get: x = 13 ∧ y = 7
Marcy bought 13 books and 7 CDs.
