Jonathan's scout troop tie-dyed sweatshirts and T-shirts last year for a fundraiser. For every 20 sweatshirts, they dyed 30 T-shirts. This year, Jonathan's scout troop will keep the same ratio of sweatshirts to T-shirts. They plan to tie-dye 60 sweatshirts.

How many T-shirts will Jonathan's scout troop dye this year?
T-shirts

If for every 20 sweatshirts, they dyed 30 T-shirts last year, then the ratio of sweatshirts to T-shirts is 20:30, which can be simplified to 2:3.

If they plan to tie-dye 60 sweatshirts this year, then the ratio of sweatshirts to T-shirts will remain the same, which means they will dye 60*(3/2) = 90 T-shirts this year. Answer: \boxed{90}.