What is the sum of the expression (9-8d)+(2c-6)+(-d+3

Ineed with question three. i don't understand how i'm supposed to achieve 3 marks.

According to a study done by de anza students, the height for asian adult males is normally distributed with an average of 66 inches and a standard deviation of 2.5 inches. suppose one asian adult male is randomly chosen. let x = height of the individual. a) give the distribution of x. x ~ b) find the probability that the person is between 64 and 69 inches. write the probability statement. what is the probability?

Graph each quadratic function and identify its key characteristics. f(x) = x^2 - 2x - 3