Heres the logic for the above example. 15 x 15 x 144 15 x 15 x 144. In fact there is no solution.
When you try to solve an equation you are starting from the unstated assumption that there actually is a solution.
When you end up with nonsense like the nonsensical equation 4 5 above this means that your initial assumption namely that the original equation actually had a solution was wrong. We have 144 144 which is a True statement it will be true for any value of the variable x. On the left-hand side. You get others by patching the two you have together.