Need help Solve for math class

Question

Ten years ago Susan's uncle was three times older than she was. Now Susan's uncle is one year older than twice her age. How old is Susan now?

Answer 1

U=1+2S

U-10 = 3(S-10)

U-10 = 3S -30

U = 3S -30 +10

U = 3S -20

1+2S = 3S -20

S = 21 = Susan's age now, 21 years old