Answer :
so percent means parts out of 100 so 17%=17/100
400 marbles
17% of 400=blue
'of' can be translated to multiply
17%=17/100
17/100 ties 400=6800/100=68
he has 68 blue marbles
400 marbles
17% of 400=blue
'of' can be translated to multiply
17%=17/100
17/100 ties 400=6800/100=68
he has 68 blue marbles