28 rowan raised $640 in a charity walk last year. this year he raised 15% more than
he raised last year. how much money did rowan raise this year?

Rowan raised 640 last year
this year he raised 15% more
percent means parts out of 100
15%=15/100=3/20
15% of 640
'of' can be translated as multiply
15%=3/20
3/20 times 640=1920/20=192/2=96
this is 15%
he raised 15% MORE SO
640+96=this year=736

he raised 736 dollars this year

640$ - is 100% - in last year in this year is 15% more, so 100+15=115% make proportion 640 is 100% x is 115% x=640*115/100=736$ Rowan raised 736$ this year