In this question, we must consider the percentage of gasoline in each mixture.

Let *A* be the **amount** of 100% gasoline required. So the amount of the 75% gasoline-oil mixture will be `8.0 − A`.

The amount of gasoline in the gasoline-oil mixture is

`75% xx (8.0 − A) = 0.75 xx (8.0 − A) = 6.0 − 0.75A`

A ratio of 15:1 means that out of 16 parts, 15 parts must be gasoline. So, the amount of gasoline **required** in the outboard engine mix is

`(15/16) xx 8 = 7.5`

So considering the amount of gasoline in each part, we have

`A + (6.0 − 0.75A) = 7.5`

`0.25A = 1.5`

`A = 6`

Therefore, we need to add `6` L of pure gasoline and `2` L of the 75% gasoline-oil mix to make the correct fuel for the scooter engine.

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