Explain the following observations: when tert-butyl bromide is treated with sodium methoxide in a mixture of methanol and water, the rate of formation of tert-butyl alcohol and tert-butyl methyl ether does not change appreciably as the concentration of sodium methoxide is increased. however, increasing the concentration of sodium methoxide causes a marked increase in the rate at which tert-butyl bromide disappears from the mixture. the base/nucleophile is ch3o−, a strong base and a strong nucleophile. the substrate is a 3° halide; therefore, the major product should be via a(n)