Ali, Ben and Calvin's savings add up to be 4 times of Dan's savings as seen in the model drawing. However, since Ali, Ben and Dan have $114.60 together, while Calvin and Dan have $172.20 together, adding both amounts will cause Dan's savings to be counted twice. Therefore, it will amount to 6 units of Dan's savings. To find 1 unit of Dan's savings, just divide by 6.