Let's denote Sabrina's current age as "S" years and her grandfather's current age as "G" years.

From the given information:

In three more years, Sabrina's grandfather will be six times as old as Sabrina was last year. This can be expressed as: (G + 3) = 6(S - 1)

When Sabrina's present age is added to her grandfather's present age, the total is 68. This can be expressed as: S + G = 68

Now, we have a system of two equations with two variables:

Equation 1: G + 3 = 6(S - 1) Equation 2: S + G = 68

Let's solve this system of equations using substitution. First, solve Equation 1 for G:

G = 6(S - 1) - 3

Now, substitute this expression for G into Equation 2:

S + (6(S - 1) - 3) = 68

Now, simplify and solve for S:

S + 6S - 6 - 3 = 68

7S - 9 = 68

7S = 68 + 9 7S = 77

S = 77 / 7 S = 11

So, Sabrina is currently 11 years old.