Math: evaluate the expression using the order of operations.

Gh bisects fgi. find the measure of hgi •15° •21° •10° •8°

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).

Extra points! find the missing dimension! need asap