Jeff and Nina each start a child-care service. Jeff spends $50 on supplies and plans to charge $10 per hour. Nina spends $30 on supplies and plans to charge $8 per hour. How many hours will Jeff and Nina have to work in order to earn the same amount of money?

Let x be the time in hour and y represents the total amount of money.

As per the given statement:

Jeff spends $50 on supplies and plans to charge $10 per hour.

⇒ y = 10x - 50 ... [1]

Also, it is given that Nina spends $30 on supplies and plans to charge $8 per hour

⇒ y = 8x - 30 ... [2]

To find the number of hours will Jeff and Nina have to work in order to earn the same amount of money.

equate [1] and [2] we get;

10x - 50 = 8x - 30

Add both sides 50 we get;

10x - 50 + 50 = 8x - 30+50

Simplify:

10x = 8x + 20

Subtract 8x from both sides we get;

2x = 20

Divide both sides by 2 we get;

x = 10 hours.

Therefore, 10 hours will Jeff and Nina have to work in order to earn the same amount of money