$\displaystyle
3{^x}+log{_2}(xy)=10
$
The derivative of the right hand side with respect to x is zero.
The derivative of the left hand side with respect to x requires differentiating $\displaystyle 3^x$ and $\displaystyle \log{_2} (xy)$ with respect to x.
Note that:
1. The derivative of $\displaystyle y = a^x$ with resepct to x is $\displaystyle (\ln a) \, a^x$
2. The derivative of $\displaystyle y = \log_{a} x$ with resepct to x is $\displaystyle \left( \frac{1}{\ln a} \right) \, \frac{1}{x}$
for appropriate values of a.
Note also that you get the derivative of xy by using the product rule .....