Let x, y, and z stand for the three numbers. We can write:

x+y+z=301 ('The sum of three numbers is 301')

y=12x-3 ('The second number is three less than twelve times the first number.')

z=7x+4 ('The third number is four more than seven times the first number')

Using Algebrator to solve for x, y, and z, we get:

x=15

y=177

z=109