A first number plus twice a second number is 7 Let the first number be x. Let the second number be y. We're given: A first number is x A second number is y Twice the second number means we multiply y by 2: 2y Plus means we add x to 2y: x + 2y The phrase is means an equation, so we set x + 2y equal to 7 x + 2y = 7