Simplify the following surd expressions

a) 5√5 - 2√5

b) 8√7 + 3√7​

The number of nails of a given length is normally distributed with a mean length of 5.00 in, and a standard deviation of 0.03 in. find the number of nails in a bag of 120 that are less than 4.94 in. long.

Anyone know? will mark brainliest if correct!

Find and simplify an expression for the area of five rows of x squares with side lengths of x centimeters.