Elliot has a total of 26 books. he has 12 more fiction books than nonfiction books. let x represent the number of fiction books and y represent the number of nonfiction books. which system of linear equations represents the situation?
a x + y = 26 and x + y = 12
bx + y = 26 and x – y = 12
cx + y = 26 and –x + y = 12
dx – y = 26 and x + y = 12

Which expresions are equivalent to the one below? check all that apply. 5x

Name each raycalculation tip: in ray "ab", a is the endpoint of the ray.

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.