when going more than 38 miles per hour the gas mileage of a certain car fits the model y=43.81 - 3.95x where x is the speed of the car in miles per hor and y is the miles per gallon of gas. Based on model what speed will the car average 15 miles per gallon
15=43.81-3.95x
subtrace 43.81 from each side, then divide both sides by 3.95
To find the speed at which the car will average 15 miles per gallon, we need to set the equation y = 15 and solve for x.
Given the equation y = 43.81 - 3.95x, we substitute y with 15 and solve for x:
15 = 43.81 - 3.95x
Let's isolate the variable x by moving the constant term to the other side:
3.95x = 43.81 - 15
Simplify the equation:
3.95x = 28.81
Now, divide both sides of the equation by 3.95 to solve for x:
x = 28.81 / 3.95
Using a calculator, we find:
x ≈ 7.3
Therefore, the car will average 15 miles per gallon at a speed of approximately 7.3 miles per hour.