Answer :
set up a simple equation with S FOR SALLY AND A FOR ANNA LOOKS LIKE THIS A+(A+.1)=3.16
Anna = a
sally = 0.1 + a
a + s = 3.16
a + 0.1 + a = 3.16
2a = 3.16 - 0.1
2a = 3.06
a = 1.53
s = 0.1 + 1.53
s = 1.63
sally = 0.1 + a
a + s = 3.16
a + 0.1 + a = 3.16
2a = 3.16 - 0.1
2a = 3.06
a = 1.53
s = 0.1 + 1.53
s = 1.63