Abby, bik, cari, dawn, and ellen collect t-shirts. abby has the most. bik has 2.5 times as many t-shirts as cari. dawn has 1/3 as many t-shirts as cari. together, abby, bik, cari, and dawn have 120 t-shirts. ellen noticed that she has double the number dawn has, plus 1. if ellen has 13 t-shirts, how many does abby have?