ciara is making a new outfit. She needs 2 1/2 yards of fabric for the shawl. She needs 1 7/8 yards of fabric for the dress. if she currently has 9/10 of a yard of fabric how much more fabric does she need to complete the outfit? if each yard is fabric cost $6.87, how much money will ciara need to make her dance outfit?

First find out the total amount you need for your fabric.
2 1/2 yards for the shawl1 7/8 yards for the dress
The total would be    2 4/8  + 1 7/8  = 4 1/8 yards
Since you already have 9/10 of a yard, just subtract from your total amount.
  3  90/80  +  72/80 = 3 18/80 = 3 9/40   *good to simplify*
She needs 3 9/40 yards more of fabric.
You already have 9/10 of fabric so you don't need to pay for it.You need to just pay for the 3 9/40 yards.
3 * 6.87 = 20.61(6.87/ 40) * 9 = 1.54575 
20.61 + 1.54575 = 22.15575 *round it*
You need $22.16 to make the dance outfit.