Adam saves $5 in the 1st week and $11 in the 2nd week.
Each week, he saves $6 more than the week before.
- How much money does he save in the 6th week?
- In which week does he save $29?
(a)
Amount that Adam saves on Week 1: $5
Amount that Adam saves on Week 2: $11 = 5 + 6 = 5 + (6 x 1)
Amount that Adam saves on Week 3: $17 = 5 + 6 + 6 = 5 + (6 x 2)
Amount that Adam saves on a certain week = 5 +(6 x (Week number - 1))
Amount that Adam saves on Week 6
= 5 + 6 × (6 - 1)
= 5 + 6 × 5
= 5 + 30
= $35
(b)
5 + 6 x (Week number - 1) = 29
6 x (Week number - 5) = 29 - 5
6 x (Week number - 5) = 24
Week number - 1 = 24 ÷ 6
Week number - 1 = 4
Week number = 4 + 1
Week number = 5
Answer(s): (a) $35; (b) 5