What is the solution to this equation? X/-4=8

Show algebraically that f and g are inverse functions f(x)=x^2/-6; g(x)=square root of 2x+12

Astick 2 m long is placed vertically at point b. the top of the stick is in line with the top of a tree as seen from point a, which is 3 m from the stick and 30 m from the tree. how tall is the tree?

Bob the builder is making 480kg of cement mix. this is made by cement, sand and gravel in the ratio 1: 3: 4