Question

find three rational number between -1 upon 2 and 3 upon 5 with proper solution

Answer 1

-1/2 and 3/5

LCM of 2 and 5 = 10
-1 * 5 = -5               So, It is -5/10
 2 * 5 = 10 

 3 * 2 = 6                So, It is 6/10
 5 * 2 = 10

Three Rational Number between -5/10 and 6/10 are -4/10 , -3/10 and -2/10. 

Hope , I helped you.

Answer 2

the formula for finding rational numbers b/w and b=  (a+b)/2
let us find three rational numbers b/w -1 and 2:
 (i) (-1+2)/2 = 1/2
(ii) (-1+1/2)/2 = (-1/2)/2 = -1/4
(iii) (1/2+2)/2  = (5/2)/2  = 5/4
the three rational numbers b/w -1 and 2 are 1/2, -1/4, 5/4
similarly , let's find three rational numbers b/w 3 and 5:
(i) (3+5)/2 = 8/2 = 4
(ii) (3+4)/2 = 7/2 = 3.5
(iii) (4+5)/2 = 9/2 = 4.5
three rational numbers b/w 3 and 5 are 4, 3.5 and 4.5