TeX source:

\begin{aligned} &\int_{\mathrm{a}}^{\mathrm{b}} \mathrm{f}(x)-\mathrm{g}(x) \mathrm{d} \mathrm{x}=\int_{\mathrm{a}}^{\mathrm{b}}\mathrm{f}(x) \mathrm{d} \mathrm{x}-\int_{\mathrm{a}}^{\mathrm{b}} \mathrm{g}(x) \mathrm{d} \mathrm{x} \\\end{aligned}