Question

Liam is saving up for a new cell phone. He uses the equation P= I + HB, where P is the cost

of the phone, I is the amount of money he started with, H is the number of hours he
babysits, and B is his hourly rate for babysitting. Which expression is equal to H, the number
of hours Liam will need to babysit to save enough money for a cell phone?

Answer 1

`H=(P-I)/(B)`

Explanation:

Given the expression: P= I + HB

Where:

• P = cost of the phone Liam is saving for.
• I = amount of money he started with.
• H = number of hours he babysits
• B = hourly rate for babysitting.

We want to find an expression for H, the number of hours Liam will need to babysit to save enough money for a cell phone.

Our goal is to isolate the variable H in the expression P= I + HB.

P= I + HB

Subtract I from both sides

P-I=I-I+HB

HB=P-I

Divide both sides by B

`(HB)/(B) =(P-I)/(B)\\\\$Therefore\\\\H=(P-I)/(B)`