Tanθ = tan(3pi/4) = -1
y/x = -1
1/x = -1
x = -1
Point is (-1, 1).
I assume you mean, that an angle and two sides are known.
A formula that can be used for irregular triangles is the cosine rule.

'b' and 'c' must be sides that are beside the angle 'A' (angle opposite 'a').
Write a proportion
centimeters / kilometers
1.5 / 45 = 0.8 / x
cross multiply
(1.5 * x ) = (45 * 0.8)
1.5x = 36
divide both sides by 1.5
x = 24
The actual distance between the two points is 24 kilometers.
Hope this helps
C. p-7 because 7 less than p implies that we would subtract 7 from p