Yesterday, Sarah collected 50 aluminum cans while Lara collected 30 more aluminum cans. Today, Sarah collected 40 while Lara collected 70 aluminum cans. How many fewer cans did they collect today than yesterday?
Thoughts? Step-by-step reasoning:
Yesterday, Lara collected 50 + 30 = 80 aluminum cans. So Sarah and Lara collected a total of 50 + 80 = 130 aluminum cans yesterday. Today, Sarah and Lara collected a total of 40 + 70 = 110 aluminum cans. Thus, they collected 130 - 110 = 20 fewer aluminum cans today than yesterday.
Thus, the answer is 20.