PSLE
Shiyun had to sew 215 windbreakers. She sewed 8 windbreakers each day from Monday to Friday and 15 each day on Saturday and Sunday. Starting on a Thursday, on which day of the week did Shiyun finish sewing all the windbreakers? Give your answer in number. (Eg Mon = 1)
Number of weekdays that Shiyun sewed on the first week = 2

Number of windbreakers that Shiyun completed for from Thursday to Sunday on the first week
= 2 x 8 + 2 x 15 
= 16 + 30
= 46

Number of windbreakers left to sew
= 215 - 46
= 169

Number of windbreakers that Shiyun could sew per week from second week onwards
= 5 x 8 + 2 x 15
= 40 + 30
= 70

Number of weeks that Shiyun needed to sew 169 windbreakers
= 169 ÷ 70
= 2 r 29

Number of days that Shiyun needed to sew 29 windbreakers
= 29 ÷ 8
= 3 r 5

Shiyun needed 1 more day to finish sewing the remaining 5 windbreakers.

Day of the week that Shiyun completed her sewing
= 3 + 1
= 4 (Thu)

Answer(s): 4