Five times the sum of a number and 7 is 8

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.

We have 339 ounces of jam to be divided up equally for 12 people how muny ounces will each person get