A pack of paper has 150 sheets. Four children each take seven sheets. How many sheets of paper are left in the pack?
We know the pack of paper has 150 sheets. And we know that four children each took seven sheets. Four times seven is 28. So we know the children used 28 sheets. So to calculate the number of sheets of paper that are left in the pack, we need to subtract the 28 sheets that we used from 150. 150 subtract 28 equals 122. There are 122 sheets of paper left in the pack.
To find the answer, first, we calculated the number of sheets the children had used by multiplying four by seven. Then, we subtracted this amount 28 from the 150 sheets there were to begin with, leaving us with 122 sheets of paper in the pack.