Suppose the ratio of Lev's age to Mina's age is 1:2 and the ratio of Mina's age to Naomi's age is 3:4

If the sum of all three ages is between 30 and 50, then how old is Mina?

1/2M + M + 4/3M = 30 to 50 (multiply eq'n by 6)

3M + 6M + 8M = 180 to 300

17M = 180 to 300

To ensure all ages are whole numbers, find all numbers between 180 and 300 divisible by 17 and 6 = 204

17 M = 204

M = 12

Lev=L

Mina=M

Naomi=N

L:M M:N

1:2 3:4

3:6 6:8

6:12 12:16

6+12+16=34

Mina is 12 years old.