Less than, because if you add 15+8 it equals 23 so less than
Answer:
10
Step-by-step explanation:
20 - 10 = 10
Answer:
2n
Step-by-step explanation:
Pythagoras 
2 squared plus 2 squared = 8 but you need to find out the root of 8,
square root of 8 is a surd, so answer in that