A candy bar and a piece of bubble gum together cost 1.50. The candy bar costs a dollar more than the bubble gum. How much does the piece of bubble gum cost, in cents?
25 cents
x+y=1.5
y=x+1
substitute in
x+x+1=1.5
-1 form either side
2x=.5
/2 /2
x=.25
