Since percent is dividing by 100, you divide 400 by 100, and you get 4. Then, you multiply 4 by 17, since blue marbles make up 17% of 400 marbles. Then finally, you get 68 blue marbles.
17% of 400 is 68. Another way u can do it is 17% of 100 four times since its easier to do. 17% of 100 is 17. we have to do this 4 times since 100 goes into 400 four times. So 17*4 =68
