60   +   90    x    \(\frac{3}{5}\)

= 60     +         54

= 114

\(60+90\times\frac{3}{5}\)

\(=60+54=114\)

60+90 x 3/5=114

\(80\text{x}\frac{1}{2}=40\)

\(80x\frac{1}{2}=40\)

80 × 1/2

= 80 ÷ 2

= 40

\(5-1,5-1\frac{1}{2}\)

=\(5-1,5-1,5\)

=\(5-\left(1,5+1,5\right)\)

=\(5-3\)

=\(2\)

= 5 - 1,5 - 1, 5 = 5 - 3 = 2.

Kết bạn cái đầu bà ý :v !!

5- 1, 5 - 1 1/2

= 5 - 1, 5 - 1, 5

= 5 - (1, 5 + 1, 5)

= 5 - 3

= 2

2\(\frac{2}{12}\)+ X = \(\frac{5}{7}\)+ \(\frac{8}{12}\)

\(\frac{13}{6}\)+ X=\(\frac{29}{21}\)

X= \(\frac{29}{21}\)- \(\frac{13}{6}\)

X=\(\frac{-11}{14}\)

\(|2^2_{12}\)\(+x=\frac{5}{7}+\frac{8}{12}\)

\(2+x=\frac{5}{7}+\frac{1}{2}\)

\(2+x=\frac{17}{14}\)

\(x=\frac{17}{14}-2\)

\(x=\frac{-11}{14}\)

\(2\frac{2}{12}+x=\frac{5}{7}+\frac{8}{12}\)

\(\frac{26}{12}+x=\frac{29}{21}\)

               x  = \(\frac{29}{21}-\frac{26}{12}\)

              x  = \(\frac{-11}{14}\)

\(12\frac{4}{5}\)=\(\frac{64}{5}\).

Ta có :

\(\frac{64}{5}+\frac{4}{5}=\frac{68}{5}\)

\(12\frac{4}{5}+\frac{4}{5}=\frac{64}{5}+\frac{4}{5}=\frac{68}{5}\)

\(12\frac{4}{5}+\frac{4}{5}=\frac{12x5+4}{5}+\frac{4}{5}=\frac{64}{5}+\frac{4}{5}=\frac{68}{5}\)

\(\frac{12}{5}+\frac{23}{4}=\frac{48}{20}+\frac{115}{20}=\frac{163}{20}\)

\(=\frac{163}{20}\)

\(\frac{12}{5}+\frac{23}{4}\) 

\(=\frac{24}{20}+\frac{115}{20}\) 

\(=\frac{139}{20}\) 

\(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{110}\)

\(=\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+...+\frac{1}{10\cdot11}\)

\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{10}-\frac{1}{11}\)

\(=\frac{1}{2}-\frac{1}{11}=\frac{9}{22}\)

= 1/2.3 +1/3.4+1/4.5+...+1/10.11

=1/2-1/3+1/3-1/4+1/4-1/5+...+1/10-1/11

=1/2-1/11

=9/22

~~~~~~~~~~~~ chúc bạn học thật giỏi~~~~~~~~~~~~~

Đặt A=1/6 + 1/12 + 1/20 +.........+1/110

A= 1/2x3 +1/3x4 +1/4x5 +......+ 1/10x11

A= 1/2-1/3 +1/3-1/4 +...........+ 1/10-1/11

A=(1/2-1/11) + (1/3 - 1/3) +.......+ (1/10 - 1/10)

A=11/22 -2/22 + 0 +...........+ 0

A=9/22

Vậy A= 9/22

\(12\frac{3}{7}\%+12\frac{5}{7}\%=\frac{176}{7}\%\)