What is 12 divided by 3 as an algebraic expression

The measure of one angle of an octagon is two times smaller that of the other seven angles. what is the measure of each angle?

The ratios 3: 9, 4: 12, 5: 15, and 6: 18 are a pattern of equivalent ratios in the ratio table. which is another ratio in this pattern?

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ac=26 and ch=8, find bh.