Factorise the following equation: 4a + 12b

Hint: Analyse the equation given in the question, try to take a common number out.
$ \Rightarrow 4a + 12b$
Split the number and variables such that there is a common term,
$ \Rightarrow 4 \times a + 4 \times 3 \times b$
As we can see $4$ is a common number in both the terms,
Therefore,
$ \Rightarrow 4 \times a + 4 \times 3b$
Taking $4$ common, we get,
Answer $ \Rightarrow 4\left( {a + 3b} \right)$
Note: There is a chance that you may take 2 common but make sure you take the greater common number out which is 4 in this case.