Larger number is x, so the smaller number is 37 - x:
x + (37 - x) = 37
“The difference” is subtraction, so we are subtracting the smaller and larger number.
“Nine more than twice the larger number” looks like 9 + 2x, and “the sum of the smaller number and three” looks like (37 - x) + 3. Because this is subtraction, we would write (9 + 2x) - (37 - x) + 3. First, distribute the negative sign:
-(37 - x) = -37 + x
We then simplify:
9 + 2x - 37 + x + 3 (subtract 3)
9 + 2x - 34 + x
-25 + 2x + x (subtract 8 and 34 then add 2x and x)
