Answer :
The first statement can be written mathematically as
[tex]x+y=105[/tex]and the second statement can be written as
[tex]x-y=21[/tex]Hence, we have 2 equations in 2 unknows. We can solve this system by elimination:
If we add these equations, we have
[tex]\begin{gathered} 2x+0=105+21 \\ \text{this gives } \\ 2x=84 \end{gathered}[/tex]therfore,
[tex]\begin{gathered} x=\frac{84}{2} \\ x=42 \end{gathered}[/tex]Since we know x, we can substitute this value into the first equation, It yields
[tex]42+y=105[/tex]and now we can isolate y:
[tex]\begin{gathered} y=105-42 \\ y=63 \end{gathered}[/tex]Finally, the answer is (63,42)