I saw in a riddles game the expression $$8?4?6=6?7?4$$ where each $?$ was to be replaced with one of $+-×÷$ to make the equation valid.
I solved it by intuition, but, is there any estimation method, even for more easy equations, to help solve this kind of riddles? I've googled, but found anything but classic equations resolutions.
Thanks in advance.
As stated by @transcenmental, it is pretty much guess-and-check, but you can sometimes narrow down the possibilities by using GCF or LCM or working backwards (for the equations that have a given answer already on one side).
But for yours, its guess-and-check.