Answer:
 16, 18 and 20
Explanation:
x - an integer
2x - an even integer (the first)
Even integers increase by 1 so:
2x+2 - next consecutive integer (the second)
3(2x+2)  - three times the second
2x+4  - the third consecutive integer
2x+2x+4 - the sum of the first and third
2x+2x+4+18 - the sum of the first and third increased by 18
2x+2x+4+18 = 3(2x+2) 
4x + 22 = 6x + 6
 -6 -6
4x + 16 = 6x 
 -4x -4x
 16 = 2x
2x = 16
2x+2 = 18 
2x+4 = 20
Check: 16+20+18=54; 3×18=54