Samuel used 1/5 of an ounce of butter to make 1/15 of a pound of jelly. how many ounces of butter are needed to make a pound of jelly?

Set up ratio problem

.2 oz butter / (1/15) lb jelly = x / 1 lb jelly

Then cross multiply the stuff opposite each other in the fractions... set it up as a multiplication problem

.2 × 1  = (1/15) × x 

.2 = (1/15)x

Multiply both sides of equation by 15 to clear out the (1/15) fraction and get x 

x = 3