Question 687232
You have learned about the basic operations on
numbers like addition, subtraction, multiplication,
and divisions,.
All algebra does is apply these operations to
symbols like {{{ x }}} and {{{ y }}} which stand for 
numbers, but which number is usually unknown.
If I say {{{ x = 3 }}}, then every time I see {{{ x }}}, 
I can replace it with {{{ 3 }}}.
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The other thing to understand is the " = " sign
Think of the " = " sign as a balance point, and if you do
something to one side, you have to do the exact same thing
to the other side.
For instance, I said
{{{ x = 3 }}}
If that's true,  I can say
{{{ x = 2 + 1 }}}
What if I subtract {{{ 1 }}} from the right side?
{{{ x = 2 + 1 - 1 }}}
{{{ x = 2 }}} But I don't want {{{ x }}} to change, so what 
should I do ? I have to subtract {{{ 1 }}} from BOTH sides
like this:
{{{ x - 1 = 2 + 1 - 1 }}}
{{{ x - 1 = 2 }}}
Is this OK ? I'll find out by replacing {{{ x }}} with {{{ 3 }}}
because I know I can.
{{{ 3 - 1 = 2 }}}
{{{ 2 = 2 }}}
I'm still OK
This is the very basics of algebra