Level 3
The average cost of some books is $30.
When a book that costs $90 is added,
the average cost of the books becomes $40.
How many books are there in the end?
Level 3
The average cost of some books is $30.
When a book that costs $90 is removed,
the average cost of the books becomes $10.
How many books are there in the end?
Level 1
The table shows the operating hours of a clinic. How many hours does the clinic operate from Sunday to Thursday altogether? (Give your answer in h.)
Level 1
The table shows the operating hours of a clinic. How many hours does the clinic operate from Sunday to Thursday altogether? (Give your answer in h.)
Level 3
The average cost of some books is $30.
If 3 of the books are now each $15 more,
the average cost of the books becomes $35.
How many books are there altogether?
