Question

how much 75 octane gas and 90 octane gas should be blended to make 15 gallons of 88 octane gas

Answer 1

75x + 90(15-x)=88(15)

75x+1350-90x = 1320

-15x + 1350 = 1320

-15x= -30

x=2

the amount of 75 octane is 2 gallons
the amount of 90 octane is 13 gallons

Hope this helps.