Question

Joaquin receives $0.40 per pound for 1-99 pounds of aluminum cans. He receives $0.50 per pound if he recycles more than 100 pounds. Is the amount of money he receives a function of weight

Answer 1

YES  
f(x)=0 when x is from (-infinity to 1) 
f(x)=0.40x when x is from [1 to 99] 
f(x)=0.50x when x is from (99 to +infinity)  
Here f(x) is what Joaquin earns which is dependent on the weight (represented by x), thus the amount of money he receives is a function of weight.