Question

add or subtract a positive integer on a number line
a number line can be used to add or subtract a positive integer.
to add a positive integer on a number line, begin at the first addend and count forward by the second addend.
to subtract a positive integer, begin at the minuend and count back by the subtrahend.
add a positive integer by counting forward on the number line.
-5 -4 -3 -2 -1 0 1 2 3 4 5
subtract a positive integer by counting back on the number line.
3 - 6 = -3

in the morning, the temperature was -15 °c. during the day, the temperature rose 20 °c. what is the temperature now?
a. begin at the first addend. make a mark on the number line at -15 °c.
b. count forward by the second addend. draw an arrow to represent counting forward by 20. circle the ending number.
c. use what you did to answer the question. the temperature now is 5 °c.

use the number line. solve. draw to show what you did.

1. erin buys a used boat for $1,200. she had an unused fishing reel that she gave to the seller who gave her a discount of $100. she also purchased a used motor for the boat for $400. how much did erin pay for her boat and its motor?

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

1. russell deposited $200 to open a new bank account before he paid $250 for his portion of the rent. his bank charged him a $50 overdraft fee. then he deposited his paycheck of $400. how much money is in russell’s account now?

-200 -150 -100 -50 0 50 100 150 200 250 300

Explanation:

Problem 1:

Step1: Initial cost of boat

Erin buys the boat for $1200, but gets a $100 discount. So the boat cost is $1200 - $100 = $1100.

Step2: Add motor cost

She also buys a motor for $400. So total payment is $1100 + $400 = $1500.

Step1: Initial deposit and rent payment

Russell deposits $200, then pays $250 rent. So account balance: $200 - $250 = -$50.

Step2: Overdraft fee

Bank charges $50 overdraft fee: -$50 - $50 = -$100.

Step3: Paycheck deposit

Deposits $400: -$100 + $400 = $300.

Answer:

$1500

Problem 2: