Answer:
i dont got the answer but u can download a pic
calculator so this picture will give u answers.
Explanation:
a)


b) First, we have that

On the other hand,

Therefore, both expressions are equal. This makes sense, because selecting k elements from a group of n is the same than specify which elements you will not select. In order to specify those elements you need to select the n-k elements that will not be selected. Hence, each time you are selecting k from n, you are also selecting n-k from n, and from that reason both combinatorial numbers are equal.
For the 2nd question......is it correct????? Because the area of square is s.s and area of rectangle is l.b
Answer is 112.5 mL
You add 45 and another 45 to get 90 mL for 200g, and divide 45 by 2 to get 22.5 for the 50g left and you add all up 90+22.5=112.5