Answer:
Jenny has 5 dimes and 16 quarters.
Explanation:
Let number of dimes and quarters are d and q in the piggy bank of Jenny.
"Jenny has total 21 dimes and quarters in her piggy bank".
By the first statement
d + q = 21 ------(1)
Second statement is "The coins are worth $4.50. or 450 cents"
1 dime = $0.10 or 10 cents, 1 quarter = $0.25 or 25 cents
10d + 25q = 450
2d + 5q = 90 ------(2)
Now we multiply equation 1 by 2 and subtract it by equation 2
(2d + 5q) - 2(d + q) = 90 - 2Ă—21
2d + 5q - 2d - 2q = 90 - 42
3q = 48
q =

= 16
Now we put q = 16 in equation number (1)
d + 16 = 21
d = 21 - 16
d = 5
Therefore, Jenny has 5 dimes and 16 quarters.