What is the total suraface area of the sequare pyramid below

Answer:
C: 280
Explanation:
An explanation of this question is what is the total surface of the pyramid,
what I did was multiply 14 x 20. How did I get the 20, I got it because since the two sides on the bottom are equal, add the 10+10 and you have 20. So the equation should be 14 x 20.
(If this doesn't help I'm sorry).