Question

Make d the subject of the formula a=cd

Answer 1

d=a/c i believe because if c*d=a then a/c=d 

Answer 2

We want to find the value of d. To do this, just separate d on one side.
To do this, divide both sides by c.

a/c = d

As you see, the c cancels the c on the right side.

d = a/c