Answer :
9/100 = x/120
the cross multiply to get:
100x = 1080
divide I080 by 100 to get 10.8
Finally add a 10.8 to 120 ( the original amount) to get $130.80
the cross multiply to get:
100x = 1080
divide I080 by 100 to get 10.8
Finally add a 10.8 to 120 ( the original amount) to get $130.80