nancy was saving to buy a brand new iphone. she had already saved $78.00. the cost of the phone that she wanted was $899 plus 8.50% plus tax. every day that she works at the car wash she makes. $42. approximately how many more days does she need to work at the car wash to have enough money for her iphone?

21.37 days.

Step-by-step explanation:

Step 1

Find the total amount Nancy is paying for her iPhone

Cost of the phone = $899

Tax = 8.50%

Amount paid for tax = 8.5% × 899

= 8.5/100 × 899

= $76.415

Total amount Nancy is paying = Tax + Cost of the phone

= $76.415 + $899

= $975.415

Step 2

We are told in the question that Nancy had already saved $78

Hence, Totally amount left for Nancy to buy her iPhone = $975.415 - $78

= $897.415

Step 3

Nancy works at a car wash and earns $42 every day.

The number of days left for her to work in the car wash in order to buy her phone is calculated as:

$42 = 1 day

$897.415 = x days

Cross Multiply

= $42 × x = $897.415 × 1 day

x = $897.415/$42

x = 21.36702381 days.

Approximately, x = 21.37 days

Therefore, Nancy has to work for 21.37 days at the car wash to have enough money for her iphone