Nannette and Nishma just got jobs working for Santa Claus. They work in Santa's hangar filling his sleigh. Nanette can fill a sleigh in m minutes while Nishma takes 5 minutes longer than Nanette to fill the sleigh. However, this Christmas they will be asked to work together filling the sleighs. When working together the two elves manage to fill the sleigh in 30 minutes.

Approximately how long does Nanette take to fill the sleigh when she works on her own ? Express answer in minutes to the nearest tenth.