I believe the answer to the question in the attached image is the 4th bubble. Be careful not to accidentally miss the formula under the worded explanation, at the bottom of the image.
The unit litre/gram is equivalent to C = something, so rearrange the equation. My reasoning:
F = Q/C
Multiply both sides by C.
CF = Q
Divide by F to get C on its own.
C = Q/F
Could someone please check if my thought process was correct, and if I have done the algebra in the optimal way?
Yes, your answer is correct.
We can check by using the units to see if we get back the correct equation.
Starting with
$$\dfrac {\text {liter}}{\text {minute}} = \dfrac {\text {grams/minute}}{\text {grams/liter}}$$
Multiply by $\dfrac {\text {grams/liter}}{\text {grams/minute}}$ to get $$\text {liter}\cdot \text {grams/liter} = \text {minute}\cdot \text {grams/minute}$$
Divide by $\text {liter}$ to get $$\dfrac {\text {grams}}{\text {liter}} = \dfrac {\text {grams}}{\text {minute}} \cdot \dfrac {\text {minute}}{\text {liter}}$$
Transform to a division problem by inverting the $\dfrac {\text {minute}}{\text {liter}}$ to get $$\dfrac {\text {grams}}{\text {liter}} = {\dfrac {\text {grams}}{\text {minute}} \div \dfrac {\text {liter}}{\text {minute}}}$$
Since $C$ is $\text {grams/liter}$, $Q$ is $\text {grams/minute}$ and $F$ is $\text {liter/minute}$, we have $$C = \dfrac QF$$ as desired.