Brandi and her mom are at a pet store. the pet store has 12 reptiles. of the reptiles,5/12 are turtles,2/12 are snakess, and the rest are lizards. what fraction of the reptiles is lizards

The pet store has 12 reptiles. 
5/12 reptiles are turtles, so 5 reptiles are turtles
2/12 reptiles are snakes, so 2 reptiles are snakes
5 plus 2 is 7
12 minus 7 is 5
there are 5 lizards
5/12 of the reptiles are lizards

The lateral side of a triangular pyramid is a triangle. in order to increase the lateral surface area, the slant height and the height should be altered