Answer:
Age of Mark is 25 years.
Step-by-step explanation:
Let the current age of Mark = x years
After 20 years, age of Mark=(x+20) years
10 years ago,age of Mark was (x-10) years.
In 20 years Mark will be three times as old as he was 10 years ago.
=> [tex]\[(x+20) = 3*(x-10)\][/tex]
=> [tex]\[(x+20) = 3x-30\][/tex]
=> [tex]\[(3x-x) = 30+20\][/tex]
=> [tex]\[(2x) = 50\][/tex]
=> [tex]\[x = \frac{50}{2}\][/tex]
=> [tex]\[x = 25\][/tex]
