angle between minute and hours hands at $7:35$ P.M I want to know what is the angle between minute and hours hands at $7:35$ P.M

I have no Idea. could any one tell me?
In $60$ minutes the hour hand moves 30 degree so in 35 minutes it would have moved 

$$\frac{30}{60} \times 35 $$
$$=17.5^\circ$$

Hour hand at $17.5^\circ$ from 7 . minute hand exactly points at 7 , so angle between minute hand and hour hand = $17.5^\circ$

I would point you to an online tool


  clock angle calculator
assuming:
h: 0-11 -> hour
m: 0-59 -> minute
s: 0-59 -> second
then

the always correct formula is:
A = 30 h - 11/2 m - 11/120 s
Angle = min {|A| , 360-|A|}   

and in your case:
h = 7
m = 35
s = 0
=> A = 30*7 - 11/2 * 35 = 17.5
Angle = min {|17.5| , 360 - |17.5|} = min {17.5 , 342.5} = 17.5