What i learnt in Algebra

W.A.L.T use in Algebra the order of operation

I learnt that in algebra if there is a missing number in the problem you put a number in the space of the missing number until you find out what the missing number is.For an example Xx3=9.It is confusing because the i put the letter x in a times problem but if you solve the problem then you can change the letter into the answer 3x3=9.And that is how you solve an algebra problem.