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# Money and Percents

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Irving has 10% as many quarters as nickels. If Irving has $5.25 in quarters and nickels, how many nickels does he have? Nov 17, 2015 ### Best Answer #2 +10 Total: 25q + 5n = 525 where q = number of quarters, n = number of nickels Also: q = 0.1n number of quarters = 10% number of nickels (10% = 0.1) Replace q in the first equation by 0.1n: 25*0.1*n + 5n = 525 or 2.5n + 5n = 525 or 7.5n = 525 so n = 525/7.5 or n = 70 There are 70 nickels. Nov 17, 2015 ### 3+0 Answers #1 +4 ok it takes four quarters to make a dallor. then all you do is mulitply 5 to 4 which give you 21 quarters then mulitply it by 10 (in 10%) then divide by 5 (for the nickels). you get 4.20 Nov 17, 2015 #2 +10 Best Answer Total: 25q + 5n = 525 where q = number of quarters, n = number of nickels Also: q = 0.1n number of quarters = 10% number of nickels (10% = 0.1) Replace q in the first equation by 0.1n: 25*0.1*n + 5n = 525 or 2.5n + 5n = 525 or 7.5n = 525 so n = 525/7.5 or n = 70 There are 70 nickels. Alan Nov 17, 2015 #3 +10 Irving has 10% as many quarters as nickels. If Irving has$5.25 in quarters and nickels, how many nickels does he have?

x = nickels ( 0.05 Cent)

y = quarters(0.25 Cent)

$$\small{ \begin{array}{rcll}  5.25 &=& 0.25 y + 0.05 x \qquad & | \qquad y = 10 \% \cdot x\\  5.25 &=& 0.25 \cdot ( 10 \% \cdot x ) + 0.05 x \\  5.25 &=& 0.25 \cdot ( \frac{10}{100} \cdot x ) + 0.05 x \\  5.25 &=& \frac{0.25 \cdot10}{100} x + 0.05 x \\  5.25 &=& 0.025 x + 0.05 x \\  5.25 &=& 0.075 x \\ 0.075 x &=&  5.25 \\ x &=& \frac{5.25}{ 0.075 }\\ x &=& 70 \end{array} }$$

He has 70 Nickels and 7 Quarters.

70 * 0.05 + 7 * 0.25 = \$5.25 Nov 17, 2015
edited by heureka  Nov 17, 2015
edited by heureka  Nov 17, 2015