Ali has $50 to spend on used books. Hardcover books cost $7 and paperback books cost $3 each. What equation in standard form determines the number x of hardcover books and the number y of paperback books he can buy?
The equation in standard form is

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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.