Students are donating money to a charity fund that helps less privileged kids. The number of $2, $5 and $10-notes donated are in the ratio of 8 : 3 : 7.
58 of the $2-notes and 10 pieces of $5-notes are taken out. The remaining notes are worth $223. How many pieces of $10-notes are there?
Let x be the number of $10-notes. The total value of the $2-notes is 2 * 8x = 16x. The total value of the $5-notes is 5 * 3x = 15x. The total value of the $10-notes is 10x. The total value of all the notes is 16x + 15x + 10x = 41x. After 58 $2-notes and 10 $5-notes are taken out, the remaining notes are worth 41x - 2 * 58 - 10 * 5 = 223. Solving for x, we get x = 11. Therefore, there are 11 pieces of $10-notes. So the answer is 11