Cole received $3 from his father in the 1st week of school and $6 in the 2nd week. Each week, he receives $3 more than the week before.
- How much money did he received in the 9th week?
- In which week did he receive $21?
(a)
Amount that Cole received on 1st Week = $3
Amount that Cole received on 2nd Week = $8
Formula:
Amount received each week = 3 + (Week number - 1) x $3
Amount received on Week 9
= 3 + (9 - 1) x 3
= 3 + 8 x 3
= 3 + 24
= $27
(b)
Week number that Cole received $21
= [(21 - 3) ÷ 3] + 1
= (18 ÷ 3) + 1
= 6 + 1
= 7
Answer(s): (a) $27; (b) 7