# How do you solve for di in #L/f= L/(di)+L/(do)#?

##### 1 Answer

Aug 29, 2016

#### Answer:

You do simple algebra.

#### Explanation:

We want di so we isolate the part containing di

(L/f)-(L-do)=(L/di)

Then we take the opposite of every fraction so we get di in the numerator's position

1 / (L/f)-(L/do) =di/L

and we multiply by L

L/ (L/f)-(L/do)=di.