Đáp án:
b=61/7
c=10/11
Giải thích các bước giải:
b,(24%+3/4+0,76+25%)×3 5/7+1 8/28
=(6/25+3/4+19/25+1/4)×26/7+9/7
=[(6/25+19/25)+(3/4+1/4)×26/7+9/7
=[ 1 +1 ] ×26/7+9/7
= 2 ×26/7+9/7
=52/7 +9/7
= 61/7
c,1/6+1/12+1/20+1/30+...+1/90+1/110
=1/2×3+1/3×4+1/4×5+1/5×6+...+1/9×10+1/10×11
=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+...+1/9-1/10+1/10-1/11
=1/2-1/11
=9/22