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Anne and Nancy use a metal alloy that is 21.8% copper to make jewelry. How many ounces of a 13% alloy must be mixed with a 29% alloy to form 140 ounces of the desired 21.8% alloy?

Respuesta :

ebrightosagie

Answer: 63.13%

Step-by-step explanation:

given data:

copper = 21.8%

0.13%x + 29%(140-x) = 21.8%(140)

open the brackets

0.13x + 40.6 - 0.29x = 30.5

collect like terms

0.13x - 0.29x = 30.5 - 40.6

–0.16x = –10.1

divide both sides by – 0.16

–0.16x / – 0.16 = –10.1 / –0.16

x = 63.13%