On 5 June to 8 June, an average of 57 sandwiches were sold and from 9th June to 13 June, an average of 20 sandwiches were sold. $276 worth of sandwiches were sold from 14 June to 24 June. Given that a sandwich was sold for $3, find the average number of sandwiches sold from 5 June to 24 June.
Number of sandwiches sold from 14 June to 24 June
= 276 ÷ 3
= 92

Number of days from 5 June to 8 June
= 8 - 5 + 1
= 4

Number of days from 9 June to 13 of June
= 13 - 9 + 1
= 5

Total number of sandwiches sold
= (4 x 57) + (5 x 20) + 92
= 228 + 100 + 92
= 420

Number of days from 5 June to 24 June
= 24 - 5 + 1
= 20

Average number of sandwiches sold
= 420 ÷ 20
= 21

Answer(s): 21