4000 is his total monthly balance.
420 + 380 = 800
800/4000 = 0.20
0.20 = 20%
He spent 20% of his monthly income on food and personal items.
P + v = 650....p = 650 - v
4p + 9v = 2925
4(650 - v) + 9v = 2925
2600 - 4v + 9v = 2925
-4v + 9v = 2925 - 2600
5v = 325
v = 325/5
v = 65.....video files
p + v = 650
p + 65 = 650
p = 650 - 65
p = 585....photo files
answer : Helena uploaded 9 times as many photo files as video files
65 * 9 = 585
One way to capture the domain of integration is with the set
Then we can write the double integral as the iterated integral
Compute the integral with respect to .
Compute the remaining integral.
We could also swap the order of integration variables by writing
and
and this would have led to the same result.