Average: Finding the missing quantity of one item given the average

The average stamps collected by 2 boys is 42.

One of the boy collected 38 stamps.

How many stamps did the other boy collect?

3 baskets have an average of 42 apples.

The total number of apples in the 2 baskets is 85.

How many Apples are in the third basket?

The average books read by Nina, Yashi and Haziq is 10.

Nina read 12 books and Yashi read 9 books.

How many books did Haziq read?

A monkey ate an average of 40 bananas per day from Monday to Thursday. How many bananas did the monkey eat on Thursday?

Day (Number)	Qty. Of bananas
Monday	45
Tuesday	38
Wednesday	41
Thursday	?

{"name":"Average: Finding the missing quantity of one item given the average", "url":"https://www.quiz-maker.com/QPREVIEW","txt":"The average height of 2 plants is 42 cm. The height of one of the plants is 38 cm. What is the height of the other plant? {answer to = 2101121}, The average mass of 3 pupils is 42 kg. The total mass of 2 of these pupils is 85 kg. What is the mass of the third pupil? {answer to = new-2}, The average age of Nina, Yashi and Haziq is 10 years. Nina is 12 years old and Yashi is 9 years old. How old is Haziq? {answer to = new-3}","img":"https://www.quiz-maker.com/3012/images/ogquiz.png"}