find the  product  using  suitable  property.
625*(-35)+(-625)*65

It is a distributive Property. The Problem is given below:

625*(-35) + (-625)*65
(You can see that the number 625 is repeating two times but their symbols are different.)
So, Now you can use the method of changing signs.
= (-625)*35 + (-625)*65
= '''(-625)*[35 + 65]'''
The Equation ''' 625*(-35) + (-625)*65''' having equal value of the equation '''(-625)*[35 + 65]'''.
Hence Proved