We know that Mary is x years old.
The age in 10 years will be x plus 10, as follows:
[tex]M_{\text{age}+10}=x+10[/tex]And the age she had two years ago was:
[tex]M_{\text{age}-2}=x-2[/tex]An example of this could be: imagine that Mary is 10 years now. In ten years, she will have:
10 + 10 = 20 years ( we add 10 to the original number). Likewise, 2 years ago, she had 10-2 = 8 years.
Therefore, the answers are two equations:
[tex]M_{age+10}=x+10[/tex][tex]M_{\text{age}-2}=x-2[/tex]