2 numbers add to 200. The first is 20 less than the second.
Let the first number be x and the second number be y. We're given:
x + y = 200
x = y - 20
Plug (2) into (1)
(y - 20) + y = 200
Group like terms:
2y - 20 = 200
Typing this equation into our search engine, we get:
y = 110 <-- This...