Deijah has $6.25.
Now, this 6.25 is comprised of 0.05s and 0.25s.
We know that there are 12 0.25s.
We now want to know how many remaining 0.05s there are.
Again, we know that the number of 0.05s he has, which is 12, multiplied by 0.05, plus the number of 0.25s he has, multiplied by 0.25, equals 6.25.
Thus, the answer is A, 0.25 x 12 + 0.05 x n = 6.25.
Only D is correct, it intersects at 90 degrees so it cant be obtuse or acute and never intersecting would be parallel lines <span />
Apparently my answer was unclear the first time?
The flux of <em>F</em> across <em>S</em> is given by the surface integral,

Parameterize <em>S</em> by the vector-valued function <em>r</em>(<em>u</em>, <em>v</em>) defined by

with 0 ≤ <em>u</em> ≤ π/2 and 0 ≤ <em>v</em> ≤ π/2. Then the surface element is
d<em>S</em> = <em>n</em> • d<em>S</em>
where <em>n</em> is the normal vector to the surface. Take it to be

The surface element reduces to


so that it points toward the origin at any point on <em>S</em>.
Then the integral with respect to <em>u</em> and <em>v</em> is



The answer could be 45 but I'm not entirely sure