x = smaller, y = larger
larger (y) is (=) 12 more than (+) smaller (x)
y = 12 + x
x + y = 74
plug one equation into the other:
x + y = 74
x + (12+x) = 74
2x + 12 = 74
2x = 74-12 = 62
2x/2 = 62/2
x = 31
y = 12 + x = 12 + 31 = 43
So smaller number = 31
and larger number = 43