Answer:
a=4
Step-by-step explanation:
if a+5=2a+1
then 5-1 = 2a-a
so 4 = a
780 (or c)
I think this is correct because 4 x 5 = 20 x 5 = 100 and 100 x 5 = 500
500 + 280 = ????
780
Answer:

Step-by-step explanation:
Use the Pythagorean theorem. 
a and b are the two side lengths
c is the hypotenuse (value across from the right angle)
Plug in the values that you are given.

Solve for x


x=

Answer:
n^2+8n+16
Step-by-step explanation:
(n+4)^2
=(n+4) (n+4)
= n^2+4n+4n+16
=n^2+8n+16