Answer:
She would need 100 ml of the 8% solution
Step-by-step explanation:
You can always answer these questions using a proportion. The numerator will represent the amount of Minoxidil, and the denominator will represent the total amount of solution
She already ha 100 ml of a 4% solution. That means that she has 4 ml of Minoxidil already

We can multiply both sides by 100 for simplicity

Assuming that this is just on a 2-D coordinate plane, we must convert the expressions on to a 3-D plane since translation cannot be done on a 2-D plane. This is done by adding a dummy coordinate that does not change. Let us use "1" for this case.
Matrix:
| 0 0 -2 |(x) = (x - 2)
<span>| 0 0 4 |(y) = (y + 4)
</span><span>| 0 0 1 |(1) = 1</span>