On a certain island, there are goats are kangaroos. You visit the island for the first time and find 150 goats and 260 kangaroo on the island. Ten year later, your return and find 280 goats and 300 kangaroos. Suppose the number of goals is a linear function of t, the number of years since your first visit.

Also, suppose the number of kangaroos is a linear function of t.

When will the number of goats be twice the number of kangaroos? Give your answer in years since your first visit.