Verify the Formula For $n = 1,2,3$ , and 4 Is It Correct

Multiple Choice

Verify the formula for $n = 1,2,3$ , and 4 . Is it correct?
$$5 + 10 + 15 \cdots + 5 n = \frac { 2 n ( n + 1 ) } { 2 }$$

A) no
B) yes