You have to find out what 15% of $78 dollars is. If you have to do this in your head and not on a calculator you can find 10%, then cut that number in 1/2 and add it to the answer. So 10% of $78 is 7.8 so $7.80. You can divide 7.80 by 2 and get 3.9 and add that to 7.8 which is 11.70. So 15% of $78 is $11.70.
Slope is the change in y over the change in x. The toy airplane would then have a slope of 3/5 and the toy helicopter would have a slope of 1/2. As 3/5 is greater than 1/2, the toy airplane would have a greater slope.
