I believe this question should be from an I-Ready test. The answer would be $20.00. Because 70% of 20.00 is 14
The surface (call it
) is a triangle with vertices at the points



Parameterize
by

with
and
. Take the normal vector to
to be

Then the flux of
across
is



So you have 3 and you want to get rid of 2 2/5. 3-2 is 1 1-2/5 is equal to three fifths, which is the answer.