Adding and subtracting decimals word problems

1. Lingley Math 7
Name: ___________________________ Class: ____ Date: ____________
Read each of the questions below carefully. Determine if you need to add or subtract -
circle the key word(s) that tell(s) you. Use front-end estimation to estimate if your
answer is reasonable.
4+ - Surpasses Learning
Goals
4 - Excelling with Learning
Goals
3+ - Consistent Proficiency
3 - Meeting Learning Goals
2 - Approaching Learning
Goals
1 - Working Below Learning
Goals
Consistently makes
efficient, logical estimates to
check for reasonable
answers.
Routinely makes effective
logical estimates to check for
reasonable answers.
Sometimes makes effective
logical estimates to check for
reasonable answers.
Rarely makes logical
estimates to check for
reasonable answers.
Consistently uses strategies
efficiently and effectively.
Routinely uses strategies
effectively.
Sometimes uses strategies
effectively.
Has difficulty using
strategies effectively.
Few calculation errors. Calculation errors are minor. Calculation errors may be
major.
Calculation errors are major.
2. Jamie earned $8.00 for her weekly allowance. At the dance she wants to buy a pop ($1.67), a
candy bar ($2.50) and a sour key ($0.25). Does Jamie have enough money to pay for all three
items?
1. Tom and Sarah ran a race at the track and field meet. Tom’s time was 90 seconds and Sarah’s
time was 2 minutes 10 seconds. How much faster was Tom than Sarah?
Adding and Subtracting Decimals
3. The iPhone 6 costs $299.55. When the new iPhone is released, the cost of the iPhone 6 will likely
decrease by $59.99. How much will the iPhone 6 cost after the decrease?
4. The Thompson family and the Robertson family have similar homes. The Thompson family sets its
thermostat to 20 C during the winter months. It’s months heating bills were: $171.23, $134.35, and
$123.21. The Robertson family used a programable thermostat to lower the temperature at night
and during the day when the family was out. The Robertson family bills were: $134.25, $103.27,
and $98.66.
a) How much money did each family pay to heat its home?
b) How much more money did the Thompson family pay?
5. A student subtracted 0.373 from 4.81 and got the difference 0.108.
a) Do you agree with the student’s answer?
b) If “yes”, show how the student calculated the answer. If “no”, what mistake did the student make?