Charlie saved $10 each day and Erika saved $
x more than Charlie each day. After 3 weeks, they were still short of $30 to buy a laptop.
- How much did the laptop cost? Express your answer in terms of x.
- If x = $15, how much did the laptop cost?
(a)
Amount Charlie saved per day = $10
Amount Erika saved per day = $(10 +
x)
Total amount both saved per day
= 10 + 10 +
x = $(20 +
x)
Number of days in 3 weeks
= 3 x 7
= 21
Total both saved in 3 weeks
= 21(20 +
x)
= 21 x 20 + 21 x
x = $(420 + 21
x)
Cost of the laptop
= 420 + 21
x + 30
= 420 + 30 + 21
x= $(450 + 21
x)
(b)
If
x = $15,
Cost of the laptop
= 450 + 21 x 15
= 450 + 315
= $765
Answer(s): (a) $(450 + 21
x) or $(21
x + 450); (b) $765
