If the average of two numbers is $$7$$, their sum is $$2\times7 = 14$$. 
If the average of two numbers is $$7$$, the numbers could be． 

a. $$3$$ and $$4$$ 
b. $$1$$ and $$8$$ 
c. $$2$$ and $$14$$ 
d. $$6$$ and $$8$$ 