Of three positive numbers, the ratio of the first and second numbers is 3:4 & that of the second and third numbers is 5:6. The product of the second and third numbers is 4320. What is the sum of three numbers?

Let the second & third numbers are 2x & 3x respectively.
ATQ,
5x*6x = 4320
30*x*x = 4320
x*x = 144
x=12
Hence, second number = 5x = 5*12 = 60
Third number = 6x = 6*12 = 72
Ratio of first & second number = ¾
Hence, first number = ( ¾)*60 = 45
Sum of these 3 numbers = 60+72+45 = 177