A gym is thinking about adding more cardio equipment for its 150 members. The member either come in the early morning or in the late afternoon. The members use treadmills and Stair Masters. There are four times as many members at the gym in the evening than in the morning. Two times as many members use treadmills than stair masters. 90 members use the thread mill in the evening. How many members use the stairs masters in the morning?

• create a Venn diagram