A mountaineer climbed 1 000 feet at a rate of x feet per hour He climbed an additional 5 000 feet at a different rate This rate was 10 feet per hour less than twice the first rate Which expression represents the number of hours the mountaineer climbed OA 6 000 3x 10 OB 6 000 3x 10 OC 1 000 OD 1 000 5 000 2x 10 5 000 2x 10