Answer:
To find the number of nickels and dimes, we can use this equation: 0.10d + 0.05n = 5.25
We are given the information that Sonji has 21 dimes (which means that d=21). We can use the equation to find the number of nickels n.
0.10d + 0.05n = 5.25
0.10(21) + 0.05n = 5.25
2.10 + 0.05n = 5.25
0.05n = 3.15
n = 3.15 / 0.05
n = 315 / 5
n = 63
Sonji has 63 nickels.
Let's check our answer.
21(0.10) + 63(0.05) = 2.10 + 3.15 = 5.25
It seems that our answer is correct.
Explanation: