Xe 5 7 10 12 y 10 13 19 f 34 f = 28, e = 4 e = 28, f = 4 f = 30, e = 2 e = 30, f = 2

5 → 13

3 · 5 - 2 = 15 - 2 = 13

7 → 19

3 · 7 - 2 = 21 - 2 = 19

12 → 34

3 · 12 - 2 = 36 - 2 = 34

Therefore we have the equations

3e - 2 = 10      |add 2 to both sides

3e = 12      |divide both sides by 3

e = 4

3 · 10 - 2 = f

f = 30 - 2

f = 28

f = 28, e = 4

60: 45 =12: 9 =4: 3 so the answer is 4: 3