Adam saves $4 in the 1st week and $10 in the 2nd week.
Each week, he saves $6 more than the week before.
- How much money does he save in the 5th week?
- In which week does he save $58?
(a)
Amount that Adam saves on Week 1: $4
Amount that Adam saves on Week 2: $10 = 4 + 6 = 4 + (6 x 1)
Amount that Adam saves on Week 3: $16 = 4 + 6 + 6 = 4 + (6 x 2)
Amount that Adam saves on a certain week = 4 +(6 x (Week number - 1))
Amount that Adam saves on Week 5
= 4 + 6 × (5 - 1)
= 4 + 6 × 4
= 4 + 24
= $28
(b)
4 + 6 x (Week number - 1) = 58
6 x (Week number - 4) = 58 - 4
6 x (Week number - 4) = 54
Week number - 1 = 54 ÷ 6
Week number - 1 = 9
Week number = 9 + 1
Week number = 10
Answer(s): (a) $28; (b) 10