Riordan saved $11 each day and Tammy saved $
x more than Riordan 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 x.
- If x = $6, how much did the mobile phone cost?
(a)
Amount Riordan saved per day = $11
Amount Tammy saved per day = $(11 +
x)
Total amount both saved per day
= 11 + 11 +
x = $(22 +
x)
Number of days in 3 weeks
= 3 x 7
= 21
Total both saved in 3 weeks
= 21(22 +
x)
= 21 x 22 + 21 x
x = $(462 + 21
x)
Cost of the mobile phone
= 462 + 21
x + 31
= 462 + 31 + 21
x= $(493 + 21
x)
(b)
If
x = $6,
Cost of the mobile phone
= 493 + 21 x 6
= 493 + 126
= $619
Answer(s): (a) $(493 + 21
x) or $(21
x + 493); (b) $619
