Help please! what does x equal

Rename mixed numbers before you can subtract are what

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

Ahypothesis is: a the average squared deviations about the mean of a distribution of values b) an empirically testable statement that is an unproven supposition developed in order to explain phenomena a statement that asserts the status quo; that is, any change from what has been c) thought to be true is due to random sampling order da statement that is the opposite of the null hypothesis e) the error made by rejecting the null hypothesis when it is true