Let number of quarters in family piggy bank = x
Let number of dimes in family piggy bank = y
Given that "there are 12 times as many dimes are there are quarters". so we can write equation:
y=12x...(i)
Given that " total change is worth $21.75".
We know that 1 quarter = $0.25 and 1 dime = $0.10
So other equation will be :
0.25x+0.10y=21.75...(ii)
Now we just need to solve both equations.
Plug (i) into (ii)
0.25x+0.10y=21.75
0.25x+0.10(12x)=21.75
0.25x+1.2x=21.75
1.45x=21.75
x=15
plug x=15 into (i)
y=12x=12*15=180
Hence final answer is given as:
Number of quarters in family piggy bank = 15
Number of dimes in family piggy bank = 180
