May I get some help with this question please?

Given f(x) = 10x + 4 and g(x) = 3x - 8, what is f(x) + g(x) ? - 7x - 4 - 13x + 4 - 7x + 4 - 13x - 4

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?

Rob spent 25%, percent more time on his research project than he had planned. he spent an extra h hours on the project. which of the following expressions could represent the number of hours rob actually spent on the project? two answers