Mathematics: Jerry 1/5 of his allowance on a book and 3/8 of the remainder of his allowance for $12.00. Calculate: A.Jerry s allowance B.The cost of the book C.The cost of the pen

Jerry 1/5 of his allowance on a book and 3/8 of the

Ответ:

ahmadfarriz4088

01.07.2021

Mathematics

Allowance = $24

Cost of book = $4.8

Cost of pen = $7.2

Step-by-step explanation:

$Let \ his \ allowance\ be\ x\\\\\frac{1}{5} \ of \ x \ on\ books\\\\\frac{3}{8} \ of \frac{4}{5} \ of \ x\ on \ pen\\\\Balance \ in \ hand = 12$

$x = \frac{1}{5}x + (\frac{3}{8} \times \frac{4}{5})x +12\\\\x = \frac{1}{5}x + \frac{12}{40} +12\\\\x =\frac{1}{5}x + \frac{3}{10} +12\\\\x - \frac{1}{5}x - \frac{3}{10} =12\\\\\frac{10x - 2x -3x}{10} = 12\\\\\frac{5}{10}x = 12\\\\5x = 12 \times 10\\5x = 120\\x = 24$

$cost \ of \ book = \frac{1}{5} \times x = \frac{1}{5} \times 24 = 4.8\\\\cost \ of \ pen = \frac{3}{8} \times \frac{4}{5} \times x = \frac{3}{8} \times \frac{4}{5} \times 24 = 7.2$

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Ответ:

shadowsnake

27.06.2021

Mathematics

x = 8

Steps:

(4x-2) + (17x+14) = 180

4x + 17x -2 + 14) = 180

21x + 12 = 180

21x = 180-12

21x = 168

x = 168/21

x = 8

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Jerry 1/5 of his allowance on a book and 3/8 of the remainder of his allowance for $12.00. Calculate: A.Jerry's allowance B.The cost of the book C.The cost of the pen

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