so far, there is no units we can see becaus we have no context what this is trying to find
so
use the distributive property which goes like this: a(b+c)=ab+ac
so
first distribute
6(60-r)=6(60)+6(-r)=360-6r
now we have
15r+360-6r=
15r-6r+360=
9r+360
there are no units associated with the expression
