Let the numbers be x and y.
Let's imagine x is the smaller of the two.
y+3 = 3x ...conceptualizing the relationsip between x and y based on the first part of the statement..
x+y-7 = 6 ...2nd part of the statement,,
Rearranging both equations:
y-3x = -3
y+x = 13
Now solving the 2 simultaneous equations by elimination:
4x = 16; x = 4
y+4 = 13; y = 9