There were 490 children altogether in two groups. Group A only consists of boys and Group B only consists of girls. There are 2.5 times as many girls as boys. Some girls joined Group B and for every 4 boys in group A. 32 more boys joined the group. The total number of girls was then 1/3 the total number of boys. Express the number of girls who joined Group B as a fraction of the number of boys who joined Group A.