Question

1. Stacy owns a hair salon and haircuts are $10. She charges hairdressers $20 per hour to rent a chair and serve clients. What is the minimum number of haircuts a hairdresser should give per hour to earn money at Stacy's salon? . . Two . . Three . . Four . . Five .

Answer 1

In one hour, hairdressers are charged with $20 for rent, and since haircuts cost $10, the minimum number of haircuts a hairdresser should give per hour to earn money is three hours. This is shows that the hairdressers would be able to earn $10 per hour. 

Answer 2

Let us make an equation to solve :
Y=mx+b (general form of a linear equation)
y=10x-20 (x is the number of haircuts,y is the amount she earns)
the minimum amount to carry out all the expenses is $20
so,
20=10x-20
20+20=10x
40=10x
40/10=x
4=x
so she must do 4 haircuts in an hour