Lesson 12 Solve Problems

- Let’s solve more problems by adding and subtracting fractions with unlike denominators.

Warm-up Estimation Exploration: Large Denominators

What is the value of the sum?

$\frac{3}{17} + \frac{17}{19}$

too low	about right	too high

Priya’s Salad Dressing Recipe

Priya has $\frac{2}{3}$ cup of olive oil. She is going to borrow some more from her neighbor. How much olive oil does she need to borrow to have enough to make the dressing?
1 tablespoon is equal to $\frac{1}{16}$ of a cup. Priya decides that 1 tablespoon of olive oil is close enough to what she needs to borrow from her neighbor. Do you agree with Priya? Explain or show your reasoning.
Priya says her recipe will make about $1 \frac{1}{2}$ cups of dressing. Do you agree? Explain or show your reasoning.

Choose a problem to solve.

Problem A:
Jada is baking protein bars for a hike. She adds $\frac{1}{2}$ cup of walnuts and then decides to add another $\frac{1}{3}$ cup. How many cups of walnuts has she added altogether?
If the recipe requires $1 \frac{1}{3}$ cups of walnuts, how many more cups of walnuts does Jada need to add? Explain or show your reasoning.
Problem B:
Kiran and Jada hiked $1 \frac{1}{2}$ miles and took a rest. Then they hiked another $\frac{4}{10}$ mile before stopping for lunch. How many miles have they hiked so far?
If the trail they are hiking is a total of $2 \frac{1}{2}$ miles, how much farther do they have to hike? Explain or show your reasoning.

Discuss the problems and solutions with your partner. What is the same about your strategies and solutions? What is different?
Revise your work if necessary.

Jada picked $4 \frac{2}{3}$ cups of blackberries. Andre picked $3 \frac{5}{8}$ cups of blackberries.

How many cups of blackberries did Jada and Andre pick together? Explain or show your reasoning.
How many more cups of blackberries did Jada pick than Andre? Explain or show your reasoning.