What does the random variable (r) for a binomial experiment of n trials represent?

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

This is so hard and it’s for a test

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.