Adam saves $5 in the 1st week and $7 in the 2nd week.
Each week, he saves $2 more than the week before.
- How much money does he save in the 8th week?
- In which week does he save $49?
(a)
Amount that Adam saves on Week 1: $5
Amount that Adam saves on Week 2: $7 = 5 + 2 = 5 + (2 x 1)
Amount that Adam saves on Week 3: $9 = 5 + 2 + 2 = 5 + (2 x 2)
Amount that Adam saves on a certain week = 5 +(2 x (Week number - 1))
Amount that Adam saves on Week 8
= 5 + 2 × (8 - 1)
= 5 + 2 × 7
= 5 + 14
= $19
(b)
5 + 2 x (Week number - 1) = 49
2 x (Week number - 5) = 49 - 5
2 x (Week number - 5) = 44
Week number - 1 = 44 ÷ 2
Week number - 1 = 22
Week number = 22 + 1
Week number = 23
Answer(s): (a) $19; (b) 23
