Based on the given details the number of nickels that she have is 63 nickels.
Formulate
0.10d + 0.05n = 5.25, d=21
Let n =number of nickels
Let d =dimes
Substitute
0.10(21) + 0.05n = 5.25
2.10+ 0.05n = 5.25
0.05n=5.25-2.10
0.05n = 3.15
Divide both side by 0.05n
n = 3.15 / 0.05
n= 63 nickels
Inconclusion the number of nickels that she have is 63 nickels.
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