A = fruit juice 40%
B= 90% juice
then
30 gallons + A = 55• C/100
30 gallons + N • (40/100) = (30 + N)• (55/100)
Now solve this equation, for N
3000 + 40N = (30+N) •55
then
3000 - 1650 = 55N - 40 N = 15N
1350 = 15 N
then
N= 1350/15 = 90
Then answer is
Should be mixed 90 gallons of 40% fruit punch
The rule of 70 is used to estimate the time it will take an initial quantity to drop to half its value:
70 : (the decreasing rate) = x ( months )
The decreasing rate = 1 - 0.97 = 0.03 = 3%
x = 70 : 3 = 23.33 = 23 1/3 = 23 months and 10 days.
Verify:
20 * 0.97^(23.33) = 9.83 ≈ 10
26.95 rounded to the nearest whole is 27, because .95 is bigger than .5. I hope this helps you.