A fuel tanker has a capacity of 7500L. The fuel needs to contain no more than 6.00% methanol. The fuel available contains 5.00% methanol. How much fuel containing 5% methanol and how much pure methanol can be added to fill the tank so that the amount of methanol does not exceed the limit?

Solution:

fuel containing 5% methanol: x

pure methanol: 7500-x

So

5%*x+(7500-x)<= 6%*7500

x>=7421.1

So

fuel containing 5% methanol should be no less than 7421.1L, pure methanol should be no more than 78.9L