Hello,Originally Posted by usm_67
I've difficulties to get the answers you mentioned above, because:
600 * 78.9 + 400 * 71.9 = 76100. That means 1 ltr of this mddle octane gas will cost 76.1 and not - as it is said in your problem - 73.9.
Let be x = amount of prem. gas.
Let be y = amount of reg. gas.
Then you get a system of linear equations:
x + y = 1000
78.9*x + 71.9*y=73.1*1000
Solve this system and you'll get:
x = 285.7 ltr
y = 714.3 ltr.