Three numbers are in the ratio 2: 3: 4 and their sum is 54. find the number

Let's guess and check.

Let's try 8

2 × 8 = 16

3 × 8 = 24

4 × 8 = 32

16 + 24 + 32 = 72 ==> too high

Let's try 6,

2 × 6 = 12

3 × 6 = 18

4 × 6 = 24

12 + 18 + 24 = 54 ==> perfect

Wow, I did not think I'd get that on the 2nd try.

So the numbers are 12, 18, and 24.