Normal distribution question for statistics class, please help someone.?

Question

I know how to z-score stuff, but Im having trouble with this weird question:

a standardized test score schievement test gives N(150,30)

Find the score of a person who scored lower than 97.5% of all scores.

Answer 1

P( X > z) = 97.5%

this corresponds to z = -1.96

z = x - mean / sigma

-1.96 = x - 150/sqrt(30)

x = 139.264