:jerome and ross each take two courses for summer school. jerome takes a math course and a science course, while ross takes a history course and a science course. for every 4 hours jerome spends studying math, he studies science for 3 hours. for every 4 hours ross studies history, he studies science for 2.5 hours. if jerome spent 16 hours studying math last week and jerome and ross studied science for the same amount of time, then ross spent hours last week.