Question 1005269
 A boy has a liter of 95% octane gas.
 He wanted to increase the concentration to 96% octane so that his motorbike would run better.
 How much of pure octane gas should he add?
We can avoid fractions if we use Milli-liters: 1 liter = 1000 ml
:
Let x = amt of 100% octane gas required to accomplish this
.95(1000) + x = .96(x + 1000) 
950 + x =  .96x + 960
x - .96x = 960 - 950
.04x = 10
x = 10/.04
x = 250 ml or {{{1/4}}} of a liter