If you spend one-fourth of a dollar, how much is left?
First divide the dollar into four equal pieces
(the denominator -- bottom number -- tells how many equal pieces are in each whole thing). 100
÷ 4 = 25. That's the amount used. What was the question?How much of the dollar is left?
You can set-up and solve this type of question as a proportion:
Use cross-products to solve: 3 times 100 = 4 times (the missing part)
3 times 100
=
4 times the amount left
300
=
4 times the amount left
300/4
=
4/4 times the amount left
75 (cents)
=
the amount left
Notice that the answer will be for whatever question you asked --the set-up can save you an extra
step later (or save you from forgetting that there was a second step).
You fold one-third of sixty napkins. How many are left?
Jack's rent is two-fifths of his income. If he earns $1500, how much is his rent?