Answer:
E = 15x - 25
Step-by-step explanation:
He makes 15 dollars an hour for x amount of hours and then subtract 25 dollars

Amplitutde:

Normally for sinx amplitude is 2 (1 +1). In the case when it is half sine amplitude is halved, therefore 0.5 +0.5 = 1 Paramers alpha = 2x does not matter because it only stretches the graph horizontally.
First let as solve all unit pirce
whistles 21.25 / 25 = $ 0.85 per unit
36 / 50 = $ 0.72 per unit
60 / 80 = $ 0.75 per unit
kazoos
10 / 25 = $ 0.4 per unit
18.50 / 50 = $ 0.37 per unit
27.20 / 80 = $ 0.34 per unit
a.) $ 0.85 - $ 0.72 = $ 0.13
b.) 10 / 25 = $ 0.4 per unit
c.) he must order 80 kazoos she should
order