pH+pOH=14 so we solve for pOH •pOH=14-7.55 —> 6.45
Now we use the pOH formula •pOH=-log[OH-] (what’s inside brackets its the concentration of OH) •6.45=-log[OH] now we pass the negative to the other side •-6.45=log[OH] and an easy way is to rise 10 by that number •10^-6.44 = [OH] •OH= 3.55x10^-7 M