Question

A school district needs 3 teachers for every 70 children. They expect to have 14,700 children in the district next year. At this time, they have 612 teachers. How many more teachers are needed?

Answer 1

They need 18 more teachers.
Set the problem up as a ratio.
 3           x
----  =  -------
70       14,700

70 x = 44,100
     x = 630

The district already has 612 teachers. So, 630 - 612 = 18 more needed.

Answer 2

There are several information's already given in the question. Let us focus on them to get to the answer.
For every 70 children, the number of teachers required = 3
Then
For every 14700 children, the
number of teachers required = (3 * 14700)/70
                                              = 630
The number of teachers in school now = 612
Number of more teachers required = 618 - 612
                                                        = 6
So 6 more teachers are required in the school.