+70 Kate bought 3 used CDs and 1 used DVD at the book store. Her friend Joel bought 2 used CDs and 2 used DVDs at the same store. If Kate spent $20 and Joel spent $22, determine the cost of used CD and a used DVD.
+2498 CD-c
DVD-d
Kate bought 3 used CDs and 1 used DVD at the book store. Her friend Joel bought 2 used CDs and 2 used DVDs at the same store. If Kate spent $20 and Joel spent $22, determine the cost of used CD and a used DVD.
2c+2d=$22
c+d=11
d=11-c
put d=11-c into 3c+d=$20
3c+11-c=20
2c=9
c=4.5
put c=4.5 into d=11-c
d=11-4.5
d=6.5
