c=¼·h(r+z) multiply both sides by 4 We have:
4c=h(r+z) Remove the brackets in the right side. We have:
4c=hr+hz Subtract hz from both sides. We have:
4c-hz=hr Divide both sides by h to get r alone.
(4c-hz)/h=r
The answer is: r=(4c-hz)/h (=4c/h - z)*
* There are lots of ways to solve this problem. For example, cx(4/h)=¼·h(r+z)x(4/h) ⇒ 4c/h=r+z ⇒ 4c/h - (z)=r+z - (z) ⇒ 4c/h - z=r ⇒r=4c/h - z, or r=(4c-zh)/h