a) A = [2/7(1/4-1/3)] : [ 2/7(1/3-2/5)]

=(1/4-1/3): (1/3-2/5)

= 1/1/4

A=3/5.6/7+3/7.3/5-2/7.3/5

A=3/5.(6/7+3/7-2/7)

A= 3/5.1

A=3/5

B =(-13.2/5+-2/9.2/5+11/9.2/5).5/2

B = 9-13-2/9+11/9).2/5.5/2

B = -13+(11/9-2/9)

B=-12

C=(-4/5+5/7).3/2+(-1/5+2/7).3/2

C = -4/5+5/7+-1/5+2/7).3/2

C = (-4/5+-1/5)+(5/7+2/7).3/2

C =-1+1.3/2

C =0

D =4/9:(1/15-10/15)+4/9:(2/22-5/22)

D = 4/9:-3/5+4/9:-3/22

D = 4/9.(-5/3+-22/3)

D=4/9.-27/3

D=-4

\(P=\) \(\frac23+\frac14+\frac35-\frac{7}{45}+\frac59+\frac{1}{12}+\frac{1}{35}\)

\(=\left(\frac23+\frac14+\frac{1}{12}\right)+\left(\frac59-\frac{7}{45}\right)+\frac35+\frac{1}{35}\)

\(=1+\frac43+\frac35+\frac{1}{35}\)

\(=2_{35}^1\)

\(Q=(5-6-2)+(\frac{-3}{4}-\frac74+\frac54)+(\frac15+\frac85-\frac{16}{5})\)

\(=-\left(3+\frac54+\frac75\right)\)

\(=\frac{113}{20}\)

A=(1/3​+2/3​)−(8/15​+7/15​)+(-1/7​+1/1/7​)=1−1+1=1;

B=(0.25−1/1/4​)+(3/5​+2/5​)−1/8

=( 1/4 - 1- 1/4) + 1 -1/8 = -1/8​
\(\).