Step-by-step explanation:
We know that tan=sin/cos, so tan(x+π/2)=

Then, we know that sin(u+v)=sin(u)cos(v)+cos(u)sin(v),
so our equation is then
Then, cos(u+v)=cos(u)cos(v)-sin(u)sin(v), so our expression is then

the x and y values makes both equations true
Explanation
a linear system is the set of 2 linear equations.
Step 1
the solution to a linear system is the coordiante where the line intersect, this coordiante satisfies both equations, then
the x and y values makes both equations true
The value of p would be 40. This is because the ratio of p:q = 10:5. this could be simplify into p:q = 2:1. Applying the ratio p:20 = 2:1, P=40.
25 is the answer to your question