A cell of emf X is connected across resistor R. The potential diffrence across wire is Y. The internal resistance of cell is:
a>{(X-Y)R}/Y b>{(X-Y)R}/X
c>(X-Y)R d>(X-Y)/R
also post how
I tried every law like Ohms Law, Kirchoffs Law but failed 2 solve.

Yep, just use Ohm's law and Kirchoff's voltage law.

Assuming "wire" means "resistor".

Draw the circuit and you'll see what unknowns need to be found.

My mathematics is very poor. so , i was unable. please post the little solution of that problem upto some steps then i would understand and do remaining steps later.

Sure. Make sure you draw the circuit, that's pretty crucial. Call the internal resistance Ri.

Apply KVL to find the voltage across the internal resistance.

Use Ohm's law to find I in the external resistor:
Y = I * R
I = Y / R

Assume I is the same everywhere in the loop. This is a trivial case of KCL.

Use Ohm's law on the internal resistance to find its value.


My approach to these things tends to be just write down as many non-trivial equations as you can think of then solve them.