Brad and Angelina can mow their yard together with two lawn mowers in 30 min. When Brad works alone, it takes him 50 min. How long would it take Angelina to mow the lawn by herself?

Equations and inequalities describe the relationship between two mathematical expressions.

A linear function can just be a constant, or it can be the constant multiplied with the variable like x or y. If the variables are of the form, x2, x1/2 or y2 it is not linear. The exponent over the variables should always be 1.