回答: #L = 39cm# #W = 6cm# 説明: #L = 2W + 27# #2L + 2W = 90# #2(2W + 27)+ 2W = 90# #4W + 54 + 2W = 90# #6W = 90〜54# #6W = 36# #W = 36/6 = 6cm# #L = 2xx6 + 27 = 39cm#