How to find the first term of an arithmetic sequence given the sum.

What is the order of the moon, earth, and sun in a lunar eclipse and a solar eclipse?

The intensity of a polarized electromagnetic wave is 12 w/m^2. part a) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=0∘ with the plane of polarization? part b) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=30∘ with the plane of polarization? part c) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=45∘ with the plane of polarization? part d) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=60∘ with the plane of polarization? part e) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=90∘ with the plane of polarization?

Connie has $660,000 she wants to save. if the fdic insurance limit per depositor, per bank, is $250,000, which of these way is distributing her money between three banks will guarantee that all of her money is insured ?