Michael saved $9 each day and Xylium saved $
k more than Michael each day. After 3 weeks, they were still short of $30 to buy a stereo system.
- How much did the stereo system cost? Express your answer in terms of k.
- If k = $12, how much did the stereo system cost?
(a)
Amount Michael saved per day = $9
Amount Xylium saved per day = $(9 +
k)
Total amount both saved per day
= 9 + 9 +
k = $(18 +
k)
Number of days in 3 weeks
= 3 x 7
= 21
Total both saved in 3 weeks
= 21(18 +
k)
= 21 x 18 + 21 x
k = $(378 + 21
k)
Cost of the stereo system
= 378 + 21
k + 30
= 378 + 30 + 21
k= $(408 + 21
k)
(b)
If
k = $12,
Cost of the stereo system
= 408 + 21 x 12
= 408 + 252
= $660
Answer(s): (a) $(408 + 21
k) or $(21
k + 408); (b) $660
