Answer:
Emily has 10 nickels, 20 dimes and 12 quarters in her piggy bank
Step-by-step explanation:
The number of dimes in Emily's piggy bank = 2 × The number of nickels
The number of quarters in it = 2 + The number of nickels
Whereby;
The number of quarters = The number nickels
The number of dimes = The number of quarters
The number of nickels = The number of dimes
The total amount = Current amount - $150
Let 'x' represent the number of dimes, let 'y' represent the number nickels, and let 'z' represent the number quarters in Emily's piggy bank, we have;
x = 2 × y
z = 2 + y
The total amount in the piggy bank is therefore;
Total = C = x×0.1 + y×0.05 + z×0.25 = 2·y×0.1 + y × 0.05 + (2 + y) × 0.25 = 0.5·y + 0.5
C = 0.5·y + 0.5
With the second condition, we have;
z = y
x = z
y = x
We get
x × 0.1 + y × 0.05 + z × 0.25 = y ×0.1 + y×0.05 + y×0.25 = 0.4·y = C - 1.5
∴ C = 0.4·y + 1.5
Which gives;
0.5·y + 0.5 = 0.4·y + 1.5
0.1·y = 1.5 - 0.5 = 1
y = 1/0.1 = 10
y = 10
Therefore;
x = 2×y = 2 × 10 = 20
z = 2 + y = 2 + 10 = 12
Therefore;
The number number of nickels in her piggy bank, y = 10
The number of dimes in her piggy bank, x = 20
The number of quarters in her piggy bank, z = 12
