The maximum speed, in miles per hour, of a cheetah is 18 more than 3 times the maximum speed of a hippo. If the maximum speed of a cheetah is 75 miles per hour, which equation could be used to find the maximum speed of a hippo, h?

Leah scored p points in the first half of the basketball game. In the second half she scored 3 more than 1/2 the number of points she scored in the first half of the game. Altogether she scored 21 points in the game. The following equation represents this situation where p represents the number of points Leah scored in the first half of the game.

$$p+\left(\frac{1}{2}p+3\right)=21$$

How many points did Leah score in the first half?