Simplify the square root of -16 + the square root of -9

I’m stuck on this equation, anyone got the answer?

Combine like terms to create an equivalent expression. make sure to simplify coefficients and constants as well. -6/5-2/3v+4/15+1/3v

The accompanying data represent the miles per gallon of a random sample of cars with a three-cylinder, 1.0 liter engine. (a) compute the z-score corresponding to the individual who obtained 42.342.3 miles per gallon. interpret this result.