Negative 18=r-3

What r and how did you get it

Ok, so if you’re saying - 18=r-3, then first you need to add 3 to each side so you can move the 3 with the - 18 so you can isolate r. (Leave it by itself). So now your equation is - 18+3=r. Next, combine like terms, so do - 18+3, which is - 15. Now you have - 15=r, so r is equal to - 15.