6.=You buy an oven for $1500 on March 20, 2013. The store gives you 4 months \"interest free\

buy an oven for $1500 on March 20, 2013. The store gives you 4 months "interest free", so on July 20, 2013 you must pay the $1500. However, the store charges an administration fee of $75, which must be paid up front when you buy the oven (March 20, 2013). What rate of simple interest, r, are you being charged for this "interest free" plan? (B) 14.25% 14.96% (D) 15.75%