Julian saved $12 each day and Emma saved $
y more than Julian each day. After 3 weeks, they were still short of $31 to buy a mobile phone.
- How much did the mobile phone cost? Express your answer in terms of y.
- If y = $20, how much did the mobile phone cost?
(a)
Amount Julian saved per day = $12
Amount Emma saved per day = $(12 +
y)
Total amount both saved per day
= 12 + 12 +
y = $(24 +
y)
Number of days in 3 weeks
= 3 x 7
= 21
Total both saved in 3 weeks
= 21(24 +
y)
= 21 x 24 + 21 x
y = $(504 + 21
y)
Cost of the mobile phone
= 504 + 21
y + 31
= 504 + 31 + 21
y= $(535 + 21
y)
(b)
If
y = $20,
Cost of the mobile phone
= 535 + 21 x 20
= 535 + 420
= $955
Answer(s): (a) $(535 + 21
y) or $(21
y + 535); (b) $955