7 of 100: XX YY ZZ

Algebra

$\begin{array} {ccccc} \huge & & & & \huge \color{#69047E}{X}& \huge \color{#69047E}{X}\\ \huge & & & & \huge \color{#D61F06}{Y}& \huge \color{#D61F06}{Y}\\ \huge + & & & & \huge \color{#3D99F6}{Z}& \huge \color{#3D99F6}{Z}\\ \hline \huge& & & \huge \color{#69047E}{X} & \huge \color{#D61F06}{Y} & \huge \color{#3D99F6}{Z} \end{array}$

If each letter represents a different nonzero digit, what must $\large \color{#3D99F6}{Z}$ be?