Answer:  The two numbers are 7 and 24. The smaller of the two numbers is 7
Step-by-step explanation:
Let the two numbers be x and y
The mathematical interpretation of the first statement  (three times a number is subtracted from another number and the difference is 3)   is  y - 3x = 3
For the second statement ( the sum of the two numbers  is 31), its mathematical interpretation is x+ y = 31
from y  = 31  - x
        we can substitute y in the equation y - 3x = 3
(31 - x)   -  3x   =  3
Then we can now proceed and solve for x
31 - x -3x  = 3
31 - 4x   =  3          subtract 31  from both-side of the equation
31 - 31 - 4x = 3 - 31
-4x   =    -28
Divide both-side of the equation by -4

x    =    7
substituting x = 7 in    y =  31 - x
y  =   31 -  7  =   24
x= 7     and y = 24
The two numbers are 7 and 24
Therefore the smaller number is 7