These numbers are "a" and "b". Sum is 64, so a+b=64 Difference is 42 so a-b=42 So you've got: [tex]+\begin{cases} a+b=64 \\ a-b=42\end{cases} \\ \overline{, \quad2a \quad \ = \ 106} \qquad /:2 \\ a=53[/tex] When a+b=64 and a=53 you've got: 53+b=64 b=11
