The formula for yearly compound interest is A(1 + r)^t
Where is A = 1000, r = 8%, t = 20

The answer is $4660.96
Well first you would start by setting up with a proportion.
In total, the girls paid $54+$22= $76
Thus 1 sister contributed $54/$76=x/100
The other sister contributed $22/$76=x/76
For each proportion, cross-multiply and simplify to get the percentage. The percentage will be the x
-12y+14-9y=14
-21y=0
y=0, x=7
Change everything into 10ths as follows:
1/10 + 2.5/10 = 3.5/10 of an hour to make one bracelet. Then change to 20ths so the numerator is a whole number.
Divide your time available by the time it takes to make one.
21
4 = 420= 15 bracelets
7 28
20
(as a whole number there was no fraction or remainder to round off)