So we know that there are 1000 mL in 1 L. We can set up an equation that allows us to solve for how many bottles are needed in order to empty the 30 L tank:

This equation then allows us to cancel out the units of mL and L, leaving us with how many bottles are needed per tank. Then we multiply straight across to give us:

The question asks us to round up to the next whole number, so
it would take 86 bottles to empty one 30 L tank.
Hello!
Here we are given a composite shape, meaning that we can divide this shape up into ways that we are given formulas to solve for legs and such.
I can see here that this can be divided into a triangle and a rectangle using a horizontal line.
The leg lengths of this triangle would be 9, because it is congruent to the bottom side of the rectangle, and 7, because it is the left side minus the right side.
This would also make a right triangle, meaning we could solve for the hypotenuse utilizing the Pythagorean Theorem.





Which is in simplest radical form.
Hope this helps!
First find the factors of 20
1 & 20
2 & 10
4 & 5
-1 & -20
-2 & -10
-4 & -5
Now find the pairs that have a difference of 1
-4 & -5
4 & 5