Answer in screen shot below
Answer:
45
Step-by-step explanation:
12 % of the marbles are blue, and
18 % of the marbles are green, so
30 % of the marbles are either blue or green.
There are 150 marbles.
30 % × 150 = 0.30 × 150 = 45
The number of blue or green marbles is 45.

Let

The curl is

where
denotes the partial derivative operator with respect to
. Recall that



and that for any two vectors
and
,
, and
.
The cross product reduces to

When you compute the partial derivatives, you'll find that all the components reduce to 0 and

which means
is indeed conservative and we can find
.
Integrate both sides of

with respect to
and

Differentiate both sides with respect to
and




Now

and differentiating with respect to
gives




for some constant
. So
