For #103 i need to know how to prove it's an identity

Mindy bought 5/8 pound of almonds and a 3/4 pound of walnuts.which pair of fraction cannot be used to find how many pounds of nuts she bought in all.

Astuntman jumping off a 20-m-high building is modeled by the equation h=20-5t^2, where t is the same in seconds. a high-speed camera is ready to film him between 15m and 10m above the ground. for which interval of time should the camera film him?

Point r divides in the ratio 1 : 3. if the x-coordinate of r is -1 and the x-coordinate of p is -3, what is the x-coordinate of q? a. b. 3 c. 5 d. 6 e. -9