60 seconds = 1 minute
60/15 = 4
12 hops in 15 seconds is the same as
4 * 12 hops in 4 * 15 seconds, or
48 hops in 60 seconds, and since 60 sec = 1 min, it equals
48 hops per minute.
14 karat gold is 58.3333...% gold
We have 75% gold and 50% gold and we need to make 200 grams of 58.3333...% gold.
A) x + y = 200
B) .75x + .50y = ( (14/24) * 200)
We multiply equation B) by -1.3333... and get
B) -x -.6666...y = -155.5555... then adding A)
A) x + y = 200 we get
.3333...y = 44.4444...
y = 133.3333... grams 12 karat gold
x = 66.6666... grams 18 karat gold
Double-Checking the answer
133.3333... * .5 = 66.6666...
66.6666 * .75 = 50.0000...
Concentration of final solution = (66.6666... + 50) / 200 = 58.3333...% which is 14 karat gold
24 ft should be your answer if I'm correct