Harold had 1400 stamps. He gave 350 of them to his brother and the rest to his sister. What Percent of the stamps did he give to his sister

What you would have to do for this problem is set up a percent, whole, and part. For example part-350, whole-1400, and the percent would be "x" because we don't know the percent he gave away. Then you put 350 over 1400 and multiply that buy x over 100. So your equation would look like this, 350/1400 X x/100. You're putting x over 100 because x represents the unknown percent, and 100 is the amount that all percent add up to. So then you multiply 350 and 100 which equals 35000. Then you multiply 1400 by x and get 1400x. Finally to get the variable by itself you divide 1400x by 1400 to get x. What you do to one side you have to do to the other. So 35000 divided by 1400 is 25. So Harold gave 25% of his stamps to his sister.