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?

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.

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