1. 88 - b Since there is 88 birds and a few of them flew away. You know b represents the amount of birds present. 2. 73 + d Since he is earning d (amount of dollars) so what you have to do is add the amount of dollars, d, to the orginial amount, which is 73. 3. 23 x g Since Kurt has 23 miles. If he drives 23 miles to a gallon and we have g gallons then we would multiply to find how far he can drive.