Billy received $1 from his aunt in the 1st week of school and $3 in the 2nd week. Each week, he receives $2 more than the week before.
- How much money did he received in the 18th week?
- In which week did he receive $17?
(a)
Amount that Billy received on 1st Week = $1
Amount that Billy received on 2nd Week = $17
Formula:
Amount received each week = 1 + (Week number - 1) x $2
Amount received on Week 18
= 1 + (18 - 1) x 2
= 1 + 17 x 2
= 1 + 34
= $35
(b)
Week number that Billy received $17
= [(17 - 1) ÷ 2] + 1
= (16 ÷ 2) + 1
= 8 + 1
= 9
Answer(s): (a) $35; (b) 9