Rhianna has $5.25 in dimes and nickels for a total of 63 coins. how many dimes does she have?

n + d = 63

5N + 10d = 525  

5n(63-d) + 10d = 525

315-5d+10d=525

5d=210

d=42

n = 63-42 = 21

Check 42 x .10 = 4.20, 21 x .05 = 1.05. 4.20 + 1.05 = 5.25

She has number of dimes = 42

Step-by-step explanation:

Rhianna has $5.25 in dimes and nickels for a total of 63 coins.

Let the number of nickels be x and the dimes be y.

Since nickels = 0.05 cent

and Dimes = 0.10 cent

Now we will form the equations

.10 y + .05 x = 5.25

5x + 10y = 525

x + 2y = 105 (1)

x + y = 63 (2)

By subtracting equation 2 from 1.

(x + 2y)-(x + y) = 105 - 63

x + 2y - x - y = 42

y = 42

By putting y = 42 in equation 1

x + 42 = 63

x = 63 - 42 = 21

Therefore

Number of dimes will be 42.

part a: 1.08

part b: 27.59