Answer: 20+35=55+20=75

Step-by-step explanation:
2 bags
7 apples
A) Instead of a lets say:
a = 1, 2 , 3
If a =1 then, (you already know there are 2 bags) you have 1 apple in each bag, making total of 2 apples
If a =2 then you are having 2 apples in each bag making total of 4 apples
If a =3, 3 apples in each bag, making total of 6 apples
Conclusion:
2 * 1 = 2
2 * 2 = 4
2 * 3 = 6
See the difference & pattern here
Now lets do with a
2 * a = 2a
B) If a = 6
then, 2*6 = 12
lets continue from a =3
2*4=8
2*5=10
2*6=12
See the pattern again
Tip: Drawing making problem understand better.
Yay, I like das stuff
I think I learned the washer method
goes like this

ok, so
actuallly, this is easier
y=49-x^2 and
y=0
see when they intersect again
they intersect at -7 and 7
if we do integrate from -7 to 7, then it wil give 0 (because integration is area under the curve), so note that they are same both sides so integrate from 0 to 7 then double the volume to get both sides
so it can't be C or D
It also can'nt be A because it should not be multipied by 4, it should be multipied by 2
basically, we don't need the washer method
remember, area=pir^2
the disk method then
we are summing up all the radii disks and squareing them
but doubleing them so

no idea why we need the inside part to be x(49-x^2), that is intersting
The answer is d because if you compare feet to yards 3 feet= 1 yard so divide 630 and 285 by 3 and then multiply them which ends up in 19,950. Your Welcome!