get a value of one textbox into another on 'onfocus' by JQ

Question

how to get a value of one textbox into another on 'onfocus' by Jquery..

for example:

 

if we put 100 in textbox1 so the value that will come in textbox2 should be less o equal to the 100(i.e, value of textbox1) by onfucus event of textbox2.

how to get this value please give the solution sir.