Weight Percentage of MTBE (methyl tert-butylether) in Gasoline : Oxygen Content

If gasoline had a hypothetical chemical formula of C8H17, and we knew the chemical formula of MTBE as CH3OC4H9, what weight (actual weight and percent by weight) of MTBE should be in the gasoline to achieve a final gasoline blend that has 2.7% oxygen by weight? Assume the densities of gasoline and MTBE equivalent at 0.75 g per cm3. Also, what is the stoichiometric air to fuel ratio (lb to lb) for the above final mixture of gasoline? How is the a/f ratio calculated in this circumstance?