Let Yancy's age be = x years
Let her sister's age be = y years
Given is , Yancy is 2 years older than 3 times her younger sister's age, so equation is formed like
.... (1)
Also given, as her younger sister is 6 years old.
So, y=6
Putting y= 6 in equation (1)



Hence, Yancy is 20 years old.