Acube has an edge length of 5 inches. you triple the side lengths. how many times greater is the volume of the new cube?

Pretty simple... if you're doubling the lengths, you're increasing them by 2 times. Take 2 and raise it to the 3rd power. If you're tripling the lengths, you're increasing them 3 times over. Take 3 and raise it to the 3rd power. And so on. 

Doubled = 2^3 = 8 
Tripled = 3^3 = 27 
Quadrupled = 4^3 = 64 
Hope this helps
~Ava~