Solve.

2d−e=7
d+e=5

use the linear combination method.

a.) (3,-1)
b.) (4,1)
c.) there is no solution.
d.) there are infinitely many solutions.

What is the product of the radical expression. (7-2square root) (8+2 square root)

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?

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.