How do you find the area of a triangular prism

Leo has b boxes of pencils. each box contains 6 pencils. he has a total of 42 pencils. the equation that represents this situation the value of b that makes the equation true the first one is b+6=42,6b=42,b=42+6,or 42b=6 the second one are 7,836 48

What is the value of x in the this question ?

Compute the standard deviation of the following set of data to the nearest whole number. 10, 10, 15, 20, 25