We need to find 30% of 20 gallons.
1) We can write a proportion
20 gallons ---- 100%
x gallons --------30%
x = 20*30/100 = 6 gallons
2) Or we can write 30% as decimal.
30% = 30/100 = 0.3
0.3 of 20 = 0.3*20 =6 gallons
Answer 6 gallons are used efficiently.
You'll be solving:
-5t^2 + 20t + 15 = 3t + 3
5t^2 - 17t - 12 = 0
(t - 4)(5t + 3) = 0
t = 4 or t = -3/5, but let's assume t ≥ 0
Step-by-step explanation: