Jesús has two twin cousins and between the three of them they are 35 years old. If Jesus' age 5 years ago was twice that of his cousins. How old is each one now?

First, from the second equation:

y - 5 = 2(x - 5)

Simplify:

y - 5 = 2x - 10

Rearranging to isolate \( y \):

y = 2x - 5

Substituting \( y = 2x - 5 \) into the first equation:

2x + (2x - 5) = 35

Combining like terms:

4x - 5 = 35

Adding 5 to both sides:

4x = 40

Dividing by 4:

x = 10

Now substituting \( x \) back into the equation for \( y \):

y = 2x - 5

y = 2(10) - 5

y = 20 - 5

y = 15

Therefore, the ages are:

\text{Jesús's cousins are } 10 \text{ years old each.}

\text{Jesús is } 15 \text{ years old.}