Vincent saved $8 each day and Yoko saved $
y more than Vincent each day. After 3 weeks, they were still short of $28 to buy a mobile phone.
- How much did the mobile phone cost? Express your answer in terms of y.
- If y = $7, how much did the mobile phone cost?
(a)
Amount Vincent saved per day = $8
Amount Yoko saved per day = $(8 +
y)
Total amount both saved per day
= 8 + 8 +
y = $(16 +
y)
Number of days in 3 weeks
= 3 x 7
= 21
Total both saved in 3 weeks
= 21(16 +
y)
= 21 x 16 + 21 x
y = $(336 + 21
y)
Cost of the mobile phone
= 336 + 21
y + 28
= 336 + 28 + 21
y= $(364 + 21
y)
(b)
If
y = $7,
Cost of the mobile phone
= 364 + 21 x 7
= 364 + 147
= $511
Answer(s): (a) $(364 + 21
y) or $(21
y + 364); (b) $511
