Factor each term separately down to prime numbers:
30a = 1*2*3*5*a
100 = 1*2*2*5*5
The factors they have in common are shown in orange  so factor them out. The factors in black are what's left of the 30a and 100 after you remove the common factors:
30100 = (1*2*3*5*a) + (1*2*2*5*5)
= (1*2*5)(3*a + 2*5) =
(10)(3a+10)
BTW, 30a100 is an algebraic expression, not an equation. An equation always has an equal sign (=).
5/15/2014

Philip P.