A camera and case together cost 110. if the camera cost 100 more than the case, how much does the case cost?

X=cost of camera

y=cost of case

x+y=110

camera is 100 more than case

x=100+y

subsitute 100+y for x

100+y+y=110

100+2y=110

minus 100 both sides

2y=10

divide both sides by 2

y=5

sub back

x=100+y

x=100+5

x=105

the camera costs $105

the case costs $5