Best Increase Method

I am working on a sweater, bottom up. I have just knit 3 inches of ribbing and now the pattern tells me to increase 20 stitches on the next round evenly.
I have 180 stitches on the needles, so I can increase one stitch every 9 stitches, am I figuring that right?
And is knit into front and back of the stitche the best increase to use?
Thank you

If the pattern now begins a stockinette stitch, the best incresae is probably to pick up from the front (with the left needle) the loop between the stitches on the row below. Then knit into the back of it. This increases one stitch and it’s very unobtrusive. .

Is that an increase that won’t leave a “hole”…and, what would be the “matching” decrease stitch?

There’s not really matching decrease and increase sts. The closest would be the KRL/KLL and k2tog/ssk. That is probably the most invisible increase, btw.

I actually like a simple backward loop increase after ribbing. I don’t see any holes left with this technique. Try it on a sample and the other increase and see which you like best.

Another vote for backward loop. I also use that for sleeve incs because it’s so obscure and clean. (I rarely used KFB because of the little aptly-named ‘bar’ at the base.)

But, as Merigold posted, try a few diff ones on your swatch and see which affords you the best transition and the look you want.