Kevin sold a box of 28 books at a yard sale for a total of $54.64. he sold the paperback books for $1.68 each and sold the hardcover books for $2.44 each. which system of equations can be used to determine the number of $1.68 paperback books, x, and the number of $2.44 hardcover books, y, that were sold at the yard sale?

a.
x + y = 28
1.68x + 2.44y = 54.64

b.
2.44x - 1.68y = 28
x + y = 54.64

c.
x + y = 28
2.44y = -1.68x + 54.64

d.
y = x - 54.64
1.68x + 2.44y = 28

Handsome jack is buying a pony made of diamonds. the price of the pony is p dollars, and jack also has to pay a 25% diamond pony tax. which of the following expressions could represent how much jack pays in total for the pony?

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?

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