a/2=b/3=c/3=20092009

b=3/2*a

c=3/2*a

(3a+b-2c)/(c-b+a)

=(3a+3/2a-3a)/(3/2*a-3/2*a+a)

=(3/2*a)/a

=3/2

2.

42*( 1/8+ 1/24+ 1/48+ 1/80+ 1/ 120+ 1/ 168)

=42*[ 1/(2*4)+ 1/(4*6)+ 1/(6*8)+ 1/(8* 10)+ 1/( 10* 12)+ 1/( 12* 14)]

=42* 1/2*( 1/2- 1/4+ 1/4- 1/6+ 1/6- 1/8+ 1/8- 1/ 10+ 1/ 10- / kloc-0// 12+ 1/ 12- 1/ 14)

=2 1*( 1/2- 1/ 14)

=2 1*3/7

=9

3.

Is the first number 3. 14?

3. 14-6.28+9.42- 12.56+ 15.7- 18.84+47. 1

=3. 14( 1-2+3-4+5-6+ 15)

=3. 14* 12

=37.68

If the first number is 20 14, then:

30 14-6.28+9.42- 12.56+ 15.7- 18.84+47. 1

=30 14+3. 14*(-2+3-4+5-6+ 15)

=30 14+3. 14* 1 1

=30 14+34.54

=3048.54

4.

(5- 1/5)*5=24

5.

Is the midpoint of the distance 18km?

The speed ratio of Party A and Party B is 9: 6 = 3: 2.

When they met, A walked more than B 18*2=36 kilometers.

Distance between Party A and Party B: 36/(3-2) * (3+2) = 180km.