Question

add or subtract a positive integer on a number line

1. ms. howard buys a car for $500 and adds a music - system that costs $200. then she adds a pair of seat - covers for $50. how much has ms. howard spent on the car so far?
2. at the beginning of the week, tideland manufacturing had an inventory of 60,000 screws. this week they received a shipment of 30,000 more screws. then they used 50,000 screws to make their tideland mowers. how many screws do they have left in inventory?
3. stem a chemical reaction is endothermic if it absorbs heat from its surroundings. it is exothermic if it gives off heat to its surroundings. in her chemistry class, lily is given a salt (ammonium nitrate) and a beaker of water at 60°f. she dissolves the salt in the water and sees that the temperature of the solution is now 50°f. did the temperature of the solution increase or decrease? by how many degrees? what kind of reaction has occurred? explain.
4. at the beginning of the month, joe has $180 in his bank account. he wants to buy a new gaming system for $250 in two weeks. his parents have offered to loan him money if he needs it. he gets $20 a week for an allowance. will he have enough money at the end of two weeks to make the purchase on his own? if not, how much will he have to borrow from his parents? explain.
5. reason can you ever add two positive integers and get a negative integer? explain.
6. reason can you subtract a positive integer from a positive integer and get a negative result? explain your answer.

Explanation:

1.

Step1: Identify costs

The cost of the car is $500, the music - system costs $200, and the seat - covers cost $75.

Step2: Calculate total cost

Add the costs together: $500 + 200+75=775$.

Step1: Calculate total received

The initial inventory is 60,000 screws and they received 30,000 more. So the total number of screws they had is $60000 + 30000=90000$.

Step2: Calculate remaining inventory

They used 50,000 screws. So the remaining inventory is $90000−50000 = 40000$.

Step1: Determine temperature change

The initial temperature of the water is 60°F and the final temperature of the solution is 50°F. The change in temperature is $60 - 50=10$°F. Since the temperature decreased.

Step2: Identify reaction type

Since the temperature of the solution decreased (absorbed heat from the surroundings), it is an endothermic reaction.

Answer:

$775$

2.