Please explain
without using tables or a calculator evaluate

The circumference of a circle is 5 pi cm. what is the area of the circle?

65 8 7 4 5 6 8 4 3 2 1 9 5 6 4 2 1 6 5 1 5 1 3 2 3 5 multiply the third number in the first row by the seventh number in the third row. add this result to the fifth number in the second row. add to this total ten times the fourth number in the third row. subtract the eighth number in the first row from the result.

Which expression will have the same sum as 3_8 + 1/4?