Every hour he bikes 13 miles:)))
2x + y = 5
x − 2y = 10
y = 5 − 2x
x − 2(5 − 2x) = 10
x − 10 + 4x = 10
5x − 10 = 10
<em>add 10 to each side</em>
<em>5x-10+10 = 10 + 10</em>
<em>5x=20</em>
5x = 0 <em>this is the error</em>
He needs to add 10 to each side
The old fare was "x"
then it got bumped up by 15%, and the new price is x + 15% of x,
so.. one could say, that "x" is the 100%, then you add a 15% to
it, to get 600
thus

solve for "x"
By Green's theorem,

where
is the circle
and
is the interior of
, or the disk
.
Convert to polar coordinates, taking

Then the work done by
on the particle is
