Word Problem Involving Add or Subtract 

Problem 1

Jamie bought a box of fruit weighing 325 kilograms. If she bought a second box that weighed 713 kilograms, what is the combined weight of both boxes?

Solution

Step 1:

Weight of the first box of fruit = 325 kilograms

Weight of the second box of fruit = 713 kilograms

The combined of the two boxes of fruit = 325 + 713 = 175 + 223

Step 2:

The denominators are different. So the LCD of the fractions or LCM of denominators 3 and 5 is 15.

Rewriting to get equivalent fractions with LCD as denominator

17×35×3 + 22×53×5 = 5115 + 11015 = (51+110)15 = 16115 = 101115

Problem 2

During the weekend, Nancy spent a total 513 hours studying. If she spent 314 hours studying on Saturday, how long did she study on Sunday?

Solution

Step 1:

Time spent studying on the weekend = 513 hours

Time spent studying on Saturday = 314 hours

Time spent studying on Sunday =

Time spent studying on the weekend − Time spent studying on Saturday

= 513 − 314 = 163 − 134

Step 2:

LCD of the fractions or the LCM of the denominators 3 and 4 is 12

Rewriting to get equivalent fractions with LCD as denominator

16×43×4 − 13×34×3 = 6412 − 3912 = 64−3912 = 2512 = 2112 hours

So, the time spent studying on Sunday = 2112 hours

Problem 3

Marcos bought apples that weighed 623 kilograms. If he gave away 315 kilograms of apples to his friends, how many kilograms of apples does he have left?

Solution

Step 1:

Weight of the apples bought = 623 kilograms

Weight of the apples given to friends = 315 kilograms

Weight of the apples left =

Weight of the apples bought Weight of the apples given to friends

= 623 − 315 = 203 − 165

Step 2:

LCD of the fractions or LCM of the denominators 3 and 5 is 15

Rewriting to get equivalent fractions with LCD as denominator

20×53×5 − 16×35×3 = 10015 − 4815 = 100−4815 = 5215 = 3715 kilograms

So, the weight of the apples left = 3715 kilograms