Find the value of $x$ in $3115_x + 4514_x = 10632_x$. 
Find the value of $x$ in $3115_x + 4514_x = 10632_x$.

I don’t understand how to even begin to go about solving this, because the bases are unknown. I don’t know if I should try tackling the bases first or the actual numbers themselves, and I’m just a bit lost. Any help, please?

We know that $x \ge 7$ since
$6$ occurs by itself.
Write
$3115_x + 4514_x = 10632_x
$
as
$(3+4)x^3+(1+5)x^2+(1+1)x+(5+4)
=x^4+6x^2+3x+2
$
or
$7x^3+6x^2+2x+9
=x^4+6x^2+3x+2
$.
We must have
$9 = 2+x$,
so $x = 7$.
As a check,
$7x^3 = x^4$ for $x = 7$.
