PSLE
Jack and Archie were paid a total of $1620 for a job they did. Jack was paid $900 more than Archie.

1. How much was Archie paid for the job?
2. Jack and Archie were paid based on the number of days they worked. Jack worked 3 times as many days as Archie. Archie was paid $12 less than Jack per day. How many days did Jack work? 

(a)
Amount that Archie was paid = 1 u
Amount that Jack was paid = 1 u + 900

Total amount paid
= 1 u + 1 u + 900
= 2 u + 900

2 u + 900 = 1620
2 u = 1620 - 900
2 u = 720

1 u = 720 ÷ 2 = 360

Amount that Archie was paid
= 1 u
= $360

(b)
Amount that Jack was paid
= 1 u + 900
= 360 + 900
= $1260

Jack worked 3 times as many days as Archie.

3 sets of Jack's salary = $1260

1 set of Jack's salary
= 1260 ÷ 3
= $420

1 set of Archie's salary = $360

Difference between each set of Jack's and Archie's salaries
= 420 - 360
= $60

Number of days in 1 set
= 60 ÷ 12
= 5

Number of days that Jack worked
= 3 x 5
= 15

Answer(s): (a) $360; (b) 15