You want to be finding out what two factors (where one of them is a perfect square) has the produce of 63. It seems like 9 x 7 (9 is the perfect square) works.

The square root of 9 is 3 so we can just have

(which just means 3 times the square root of 7).
The second option with the chart
There are 16 girls and 12 boys which means the ratio of number of girls to the numbers of boys in her class is 16:12 and 4:3 when simplified.
Answer:
to reflect the line and record readings