(a) If we let x be the number of miles and y be the total cost, the equation for relating the number of miles and the total cost would be,
y = 0.4x + 48
(b) If the rental cost is 60,
60 = 0.4x + 48
The value of x from the equation is 30.
(c) You may prepare the table of values by allowing x be any number and then solve for y until we arrive with an answer for y being equal to 60.
Answer:
n=21
Step-by-step explanation:
We must find n.
Remember PEMDAS. First we must do the Parentheses. Lets do distributive property by multiplying a number that is immediately outside the parentheses with each number inside the parentheses. Lets do this one side at a time.
First lets do 5(n - 7). We get 5n - 35
Now 2(n + 14) is 2n + 28
Okay...... now we have 
Now lets do OPPOSITES!!!! We must do the opposite of each thing to both sides.
The opposite of -35 is positive 35. Lets add 35 to both sides. We get:

Now lets do the opposite of 2n which is -2n

this is looking quite nice isnt it..........
The opposite of 3 times n is 3 DIVIDED BY n. So lets divide both sides by 3

amazing.......