Gabriella is x years old. her sister, felicia, is six years older that she is. their mother is twice as old as felicia. their aunt, tanya, is x years older than their mother. write and simplify an expression that represents tanya's age in years.

In this case, Gabriella = x 
Felicia is 6 years older than Gabriella's age. this makes their equation F = x + 6
Their mother is twice as old as Felicia. this makes their equation M = 2(x + 6)  or  2x + 12
Tanya is the mothers age + Gabriella's age. this makes the equation
A = 2x + 12 + x = 3x + 12
when you solve the equation you will get the equation 3x + 12, which is the simplified expression that represents Tanya's age.