The sum of three consecutive even integers is 144.

If you divide 144 by three you get 48. Then when you subtract one from 48 you get 47. When you add one to 48 you get 49. So the three consecutive numbers are 47, 48, 49

The 3 consecutive even integers  are n , n + 2 and n + 4  so
3n + 6 = 144
3n = 138
n = 46

the 3 numbers are 46, 48 and 50.

No he does not because he can only cover 12 square feet from 15 square feet which he will still need 3 more. this is because if 3×5=15 square feet and 15-12=3 which thats the answer