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

In the United States  among 60 percent of the space on the pages of newspapers is reserved for  advertising

A. among

B. of the space

C. is reserved

D. advertising

Ta có:(2^x+1-8).(5²-5x)=0

=>2^x+1-8=0;5²-5x=0

=>2^x+1=8;25-5x=0

=>2^x+1=2³;5x=25

=>x+1=3;x=5

=>x=2,5

Vậy x=2,5

Cho m gam dung dịch glucozơ 20% tráng bạc, phản ứng hoàn toàn sinh ra 64,8 gam bạc. Giá trị của m là

A. 270 gam

B. 135 gam

C. 54 gam

D. 108 gam