# Decrementing one number, incrementing another, while keeping the same relation to one another

This is a game development question related to math. Apologies if I shouldn't be asking this here, but I'm not good at math and need help with increasing the speed of my game.

I have one number responsible for the speed at which the screen appears to be moving horizontally. It's 80 (screen points).

The other number is 1 (second), and it dictates the time it takes an object to move a set vertical distance.

Increasing the 80 number will increase the horizontal speed, and decreasing the 1 number will increase the object's vertical speed.

After each level, I'd like to increment 80 and decrement 1.

Is there a number that I can increment 80 by, and a number I can decrement 1 by, so that both speeds remain the same, relative to each other? If not, what would be the best numbers I could use so that it isn't too apparent that the 2 speeds have gone out of sync? If this is the case, the vertical speed would need to be getting faster than the horizontal.

Ideally, I'd like to get as close as possible to incrementing by 1 and decrementing by 0.01.