please help me out!!

What is the largest possible integer that can be chosen as one of five distinct positive integers whose average is 10?

What is the sum of the rational roots of f(x)=x^3−4x^2+16x−39?

How many positive integers less than 1000 are odd but not a multiple of 5

A regular polygon has interior angles of 150∘. A,B,C,D are 4 consecutive points of this polygon. What is the measure (in degrees) of ∠ADC?

A bag contains 150 balls numbered 1 through 150. Three balls are drawn and placed on the table. The probability that the balls were drawn in increasing order can be expressed as a/b where a and b are coprime positive integers. What is the value of a+b?