How do you find rate?

Alicia puts $400 in a bank account. each year the account earns 5% simple interest. how much money will be in her bank account in six months?

Geometry in the diagram, ∠abc is a right angle. ∠dbc = 30°27'40". find the measure of ∠abd.

Find the actual dimensions of the box. the side length are in meters and integers. the surface area of the box is 104 m2 and volume of the box is 60 m3.