tong cua 5 so la mot so duong thi tong cua 30 so la: 6.5 = 30 la so duong( +).(+) = (+)

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

The mountain climbers proceeded forward on their long trek up the side of the mountain.

A. The 

B. proceeded forward

C. on

D. side