Trying to figure out the right pixel dimensions to convert to 360dpi for print

Hi,

I'm trying to use Adobe Express to make some 4x5, 8x10, and one larger size cards with written words, and Adobe Express is just a lot easier ot make cards like this than Photoshop.  But Express will only allow 72dpi stupidly, and I can't figure out what the pixel dimensions should be for say the 8x10 card, which I want to eventually be 8x10" @360dpi 

Could anyone help me with a way of figuring this out?  

an 8x10 @360dpi is 2880x3600 pixels.  But if I start with those pixel dimensions, than when I change the image to 360dpi in photoshop, the image will become smaller.  And I can't find a way to calculate the right dimensions to start with .  

Maybe I'm missing something.  

Thank you!