Answer:
(a) Equation: 
(b) 7.5 gallons
Step-by-step explanation:
Given
Current Gas = 10 gallon
Every Hour = -1.25 gallon
Solving for (a): An equation for the scenario
This question represents an Arithmetic Progression and will be solved using the following formula:

Where


Substitute these values in the formula


Collect Like Terms


Solving for (b): In this case, n - 3
Substitute 3 for n in 



<em>7.5 gallon of gas left</em>
Answer: A
Step-by-step explanation:
They should take 5 boxes.
If there is 8 boxes with a total of 56 boxes, you would do 56/8 to find how many sweaters are in each box. This comes out to be 7 sweaters per box. If you want 35 sweaters, you would do 35/7 to find how many 7 sweater boxes you need to reach 35.