Final answer:
The total profit if WashWheels washes 45 cars in a day is $3,033.
Step-by-step explanation:
To find the total profit if WashWheels washes 45 cars in a day, we can substitute the value of x = 45 into the profit function g(x) = 1.8x^2 - 4x.
So, the total profit = g(45) = 1.8(45)^2 - 4(45).
Simplifying this expression, the total profit is $3,033.