Determine if the following relation is a function or not

How do you use the additive inverse to evaluate an expression that uses subtraction in a full sentence

The height of a triangle is 4 in. greater than twice its base. the area of the triangle is no more than 168 in.^2. which inequalitycan be used to find the possible lengths, x, of the base of the triangle?

The size of a certain cell is 2.5*10^-9m. another cell is 1.5*10^3 times larger. how large is the larger cell in scientific notation?