1. Proportions for WHAT? Cooking!
Joe has to make 40 gallons of soup for the rescue mission. In the past it takes 4 onions for every 5 gallons of soup. Before he goes out and buys supplies, how many onions will he need to buy?
First, Joe’s got to set up his proportion n
5 =
Next, cross multiply
160 = 5n
Isolate the variable by dividing by 5
32 = n so Joe needs 32 onions

2. Proportions for WHAT? Building
Anna wants to hang some drywall. She knows that 3 pieces of drywall covers 12 feet of wall. To finish her basement, she has to cover 140 feet of wall. How many pieces of drywall does she need to purchase?
First, Anna’s got to set up her proportion n =
Next, cross multiply n
420 = 12n
Isolate the variable by dividing by 12
35 = n so Anna needs 35 pieces of drywall