# Adding and Subtracting to Solve Problems

Warmup

Solve as many problems as you can in this exercise.

Activity #1

Explore Steps involved in Adding Fractions.

• Enter two fractions to add and press the Enter key. ​
• Click to continue.
• Use the “Up” “Down” arrows to find a common denominator. As soon as you find one, the applet will notify you.
• Then, click to continue.
• Multiply each pair of fractions on either side of the plus sign and enter their products in the boxes. If you do that correctly, the applet will again notify you.
• Click to continue.
• Click . And you are done.
• Click and do some more.

Activity #2

Plot Points on a Coordinate System.

• Plot these points on the coordinate grid: A=(5,4), B=(5,-2), C=(-3,-2), D=(-3,4) and answer the questions below.

Activity #3

Application of Addition and Subtraction.

A store tracks the number of cell phones it has in stock and how many phones it sells.

The table below shows the inventory for one phone model at the beginning of each day last week. The inventory changes when they sell phones or get shipments of phones into the store.

• Study the table below for the cell phones inventory, and answer the questions that follow.

(1.) What do you think it means when the change is positive?

(2.) What do you think it means when the inventory is negative?

(3.) Based on the information in the table, what do you think the inventory will be at on Saturday morning? Explain your reasoning.

(4.) What is the difference between the greatest inventory and the least inventory?

Challenge #1

The departure from the average is the difference between the actual amount of rain and the average amount of rain for a given month. The historical average for rainfall in Albuquerque, NM for June, July, and August is shown in the table below.

(1.) Last June only 0.17 inches of rain fell all month.

(2.) The departure from the average rainfall last July was -0.36 inches.

Challenge #2

The table shows four transactions and the resulting account balance in a bank account, except some numbers are missing. Fill in the missing numbers.

Challenge #3

(1.) Without computing,

(2.) Without computing,

Quiz Time