Let the missing integer be x.
Now,
4(28) = 4(20) + 4(x)
According to distributive property,
A(B+C) = AB + AC
Substituting dsitributive property into the equation, we get,
4(28) = 4(20) + 4(28 - 20)
4(28) = 4(20) + 4(8)
Thus, the missing integer is 8.
(Check it!)
4(28) = 4(20) + 4(8)
112 = 80 + 32
112 = 112 ;
or, LHS = RHS.
Hence proved.
