Question

-21×(-3)+(-7) = (-21)×(-3) + (-21) × (-7)

Answer 1

We know that ,
L.H.S = -21×(-3)+(-7)
             {can be written as } 
          = (-21)[ (-3) + (-7) ]           -----------------Eq(1)

R.H.S =(-21)×(-3) + (-21) × (-7)
            {taking (-21) common }                 
          =(-21) [ (-3) + (-7) ]          ----------------- Eq(2)
 
 From eq (1) and (2)
L.H.S =R.H.S
 
 ------------------------------------------------------------------------------------------------------------------
Best of luck ;)  
ROYALJATT