Observe attached picture.
On picture we have:
A = height of flagpole = x ft
B = length of flagpole's shadow = 24 ft
C = height of sign = 6 ft
D = length of sign's shadow = 3 ft
When we draw a picture representing this problem we can also add another line marked in red. This way we can see that we have two right-angle triangles. We can see that both have same angle marked with α.
We can apply trigonometry rules to find height of flagpole.
From small triangle containing sign we can find tangens function:

Similarly we can do for large triangle containing flagpole:

We see that these two equations have same left sides. This means that their right sides must also be same:

We can solve for A:

Height of flagpole is 48 feet.
Answer
She used 6/15 litres of oil in January
Explanation
We are given that, in January, she used 3/5 of the amount of oil she used in February.
We are also given that, she used 2/3 litres of oil in February.
Therefore, amount of oil used in January is:
3/5 • 2/3 = 6/15
She used 6/15 litres of oil in January
If she needs 1,000 ribbons at 3.72 inches each, She will need 1,000 x 3.72 which equals 3720 inches of ribbon.
This can be converted into feet by taking 3720 inches and dividing by 12 inches in a foot.
This will an answer of 310 feet.