Also you can compute the slope of the budget line and compare it with the inequality p(xe)/p(x0)<=1, p(xe) will be a term in R from that compute the maximum value that R can take...This is because according to the utility function given, goods are perfect substitute so in order to get xe s.t xe>0, its per unit price has to be less than one..you can use either of the inequalities from the problem formulated...!!!!
"I don't ride side-saddle. I'm as straight as a submarine"