What is the property of 7+(a+b)=7+a)+b

All per-unit concepts rely on ratios, meaning, to provide a type of measurement

Which of the following expressions is equal to 2x^2+8

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?