You have to subtract 4 from 7 and then add 5 and 3 then add 8 and 2 then multiply 10 with 3 to get 30.
Of means multiply.
30%=0.3
30*0.3=9
9 students play in the school band
(a) You can parameterize <em>C</em> by the vector function
<em>r</em><em>(t)</em> = (<em>x(t)</em>, <em>y(t)</em> ) = <em>P</em> (1 - <em>t </em>) + <em>Q</em> <em>t</em> = (2 - 2<em>t</em>, 7<em>t</em> )
where 0 ≤ <em>t</em> ≤ 1.
(b) From the above parameterization, we have
<em>r</em><em>'(t)</em> = (-2, 7) ==> ||<em>r</em><em>'(t)</em>|| = √((-2)² + 7²) = √53
Then
d<em>s</em> = √53 d<em>t</em>
and the line integral is

(c) The remaining integral is pretty simple,

This is the same as averaging. You add them and divide by 2.
((m/n) + (p/q))/2 would be a number in between m/n and p/q.
Do note that n and q must be nonzero, but luckily that is a given.