365: Red; January 13, THIS is when I'm ever going to need maths

With few exceptions, there will come a point when a kid mutters, "When am I ever going to use maths in real life?"

I'm trying to knit a sweater based on one I saw on Pinterest. That one is cool but it's made so the body part only covers the body to the top of the bust line. I'd rather be covered up, so am trying to work out a pattern that includes decreases and increases over a particular distance in inches.

This would be the part where all that algebra and plotting stuff would come in handy.