d. since angle b is 100, arc AC must be two times that amount, which is 200
e. opposite angles of a quadrilateral are supplementary (adds up to 180). to find CDA, you have to do 180 minus 100 (which is the measure of angle B) to get 80
g. opposite angles of a quadrilateral are supplementary (adds up to 180). to find BCD, you need to do 180 minus 70 (which is the measure of angle A) to get 110
