Solve for the variable a d =a+b-c/3

Hey there,
solving for a is just like you think of all other letter as a constant
i.e the only variable is a
so you need to subtract b as a start
      d=a+b-c/3
-b             -b


    -b+d=a-c/3                now it's time to add c/3 (isolate a by itself in one side)

     -b+d=a-c/3
+c/3         +c/3

c/3-b+d=a

Hence you have solved for a