Gabriel used the expression 2.5x + 2y – 2 to represent his total cost, and 28 – 2.5x – 2y to represent the amount of change he should receive from $30. what was gabriel’s error?

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.