15.1 Add and Subtract Fractions to Solve Problems

15.1 Add and Subtract Fractions to Solve Problems

I can add and subtract fractions greater than one with like denominators to solve real-world problems.

Multiple Choice

Launch Problem

• A

• B

• C

• D

Spark Your Learning

Mrs. Hanson needs 9 servings of almonds. Each serving weighs 1/4​​ pound. She already has 3/4​ ​pound of almonds. How many more pounds of almonds does she need?

Multiple Choice

How many more pounds of almonds does Mrs. Hanson need?

• 2 pounds

• 7/4​​ pounds

• 6/4​​ pounds

She needs 6/4 pound more.

Mrs Hanson needs nine 1/4​​-pound servings, or 9/4​​ pounds of almonds. Subtract the fraction of a pound of almonds Mrs. Hanson has from the total amount of almonds she needs to find the difference. 9/4 ​− 3/4 ​= 6/4​, or 12/4​​ pounds of almonds.

Build Understanding

Brooke and Bailey each bring 1/4​​-pound bowls of grapes to serve at a class party. This shows the number of bowls each person brings. How many pounds of grapes do they bring?

Multiple Choice

What does a unit fraction represent in the problem?

• the number of bowls that Bailey brings

• 1 bowl of grapes

• the number of bowls each person brings

The unit fraction represents one bowl of grapes.

Multiple Choice

How many bowls of grapes do Brooke and Bailey bring?

• 2

• 5

• 7

They bring 7 bowls of grapes.

Brooke brings 5 bowls of grapes, and Bailey brings 2 bowls of grapes. Altogether, Brooke and Bailey bring 7 bowls of grapes.

Multiple Choice

So what is the weight of the grapes the two students bring?

• 7/4 pounds

• 2 pounds

• 7 pounds

Step it Out

Mrs. Hanson makes a snack mix with this bag of raisins and this box of cereal. The students eat 14/12​​ pounds of snack mix at the party. How much snack mix is left?

Fill in the Blanks

How much snack mix does Mrs. Hanson make?

It's 17/12.

Add 9/12​​ pound of cereal with 8/12​​ pound of raisins to have 17​/12​ pounds of snack mix.

Multiple Choice

Which equation can be used to model this part of the problem and find how much snack mix is left?

• 17/12 ​− 14/12 = 3/12​​; 3/12​ pound left

• 17/12 ​−8/12 ​= 9/12​​; 9/12 pound left

• 17/12 ​− 9/12 ​= 8/12​​; 8/12 pound left