Question 93892
That's right, here is a method, easy to understand.
:
"The difference of two numbers is 33".
Let x =  1st number
Then the 2nd number = (x+33) 
:
"The second is 7 less than 3 times the first." 
 (x+33) = 3x - 7
 x - 3x = -7 - 33
 -2x = -40
   x = -40/-2x
   x = +20