The manual for your boat engine calls 91 octane gas. the gas stations by your house only sell 87 and 93 octane. if the boat's tank holds 30 gallons, how many gallons of each should you buy for a 91 octane mix?

I not exactly sure if this is right but with the numbers that you are given, you can do a simple division problem of 91/30=3.0999 because you don't want decimals, you need a solid number of gallons you must buy you would have to buy 4 gallons for that 91 octane mix, leaving you with some gas.

Hope I helped you!