John saved $9 each day and Opal saved $
m more than John each day. After 2 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 m.
- If m = $11, how much did the mobile phone cost?
(a)
Amount John saved per day = $9
Amount Opal saved per day = $(9 +
m)
Total amount both saved per day
= 9 + 9 +
m = $(18 +
m)
Number of days in 2 weeks
= 2 x 7
= 14
Total both saved in 2 weeks
= 14(18 +
m)
= 14 x 18 + 14 x
m = $(252 + 14
m)
Cost of the mobile phone
= 252 + 14
m + 31
= 252 + 31 + 14
m= $(283 + 14
m)
(b)
If
m = $11,
Cost of the mobile phone
= 283 + 14 x 11
= 283 + 154
= $437
Answer(s): (a) $(283 + 14
m) or $(14
m + 283); (b) $437
