The area of a circle is 100 pi ft2. What is the circumference, in feet? Express your answer in terms of pi

The volume of gas a balloon can hold varies directly as the cube of its radius. imagine a balloon with a radius of 3 inches can hold 81 cubic inches of gas. how many cubic inches of gas must be released to reduce the radius down to 2 inches?

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?