Question

©MP.4 Model with Math

when Mary was born, she weighed 8 pounds. When she was 10 years old, she weighed
10 times as much. How much more did Mary weigh when she was 10 years old than
when she was born? Use Exercises 1-2 to answer the question.
1. Draw a picture, write and solve an equation to find Mary's
weight, w, when she was 10 years old.
2. Draw a picture, and write and solve an equation to find the
difference, d, between Mary's weight when she was 10 years
old and when she was born.​

Answer 1

The drawings are in the picture attached and the explanations are below.

Question 1.

• Equation: w = 10 × 8 lb

• Solution: x = 80 lb

Question 2:

• Equation: d = 10×8 lb - 8 lb
• Solution: d = 72 lb

Step-by-step explanation:

Question 1:

• Statement 1: Mary was born, she weighet 8 lbs
• Statement 2: When she was 10 years old weighed 10 times as much

w = 10 × 8 lbs = 80 lbs

Explanation of the drawing:

Each cell represents 8 lbs, which was the weight when she was born. There are 10 cells, representing that the amount 8 lbs is repeated 10 times.

Then, the multiplication is represented an abbreviated sum:

• 8 + 8 + 8 + 8 + 8 + 8 + 8 + 8 + 8 + 8 = 10 × 8 = 80

Question 2:

• Statement: find the difference, d, between Mary's weight when she was 10 years old and when she was born.​

d = 80 lbs - 8 lbs = 72 lbs

↑ ↑ ↑ ↑

difference 10 years old born solution

Explanation of the drawing:

• When you subtract one cell (8 lb) from ten cells (10 × 8 = 80 lb), you obtain nine cells ( 9 × 8 lb = 72 lb).