Question

(a/6)-10=(a/3)

Answer 1

We have that
(a/6)-10=(a/3)
(a-60)/6=a/3
3*(a-60)=6*a
(a-60)=(6/3)*a
(a-60)=2*a

the answer is
(a-60)=2*a


alternative method shorter
(a/6)-10=(a/3)
multiply all expression by 6
6*(a/6)-6*10=6*(a/3)
a-60=(6/3)*a
a-60=2*a