Just divide 49 by 16 and you get 3.06 so you know 16 can only completely go into 49 3 times.
You can also add 16 to 16 many times until you go over 49. So you can only add 16 + 16 + 16 to eachother 3 times without going above 49 which also gives us our answer.
We need to put all elements in one side so that the other side is 0. Then, apply quadratic formula to solve the problem. To do that, we need to subtract both sides by 4.