It's not clear what is to be solved. Nevertheless, the three points a, b and c can be plotted on Cartesian coordinates based on a vertical axis running North to South (top to bottom or positive to negative) and a horizontal axis running West to East (left to right or negative to positive). The distances given I understand to be distances from the origin and the angles represent the angles between lines joining the origin to each of the points and one or other of the axes. East of South is the angle between the negative y axis and the line on the positive side of x; N30W is the angle between the line and the positive y axis on the negative side of x; S of W is the angle between the line and the negative x axis on the negative y side. Point a becomes (5cos30, -5cos60); point b is (-7cos60, 7cos30); c is (-10cos70, -10cos20). All dimensions are cm because N=1cm. The trigonometric ratios are: cos60=0.5, cos30=sqrt(3)/2, cos70=0.342 and cos20=0.940. Sqrt(3)=1.732. All decimals to three places accuracy. Joining the three points together we get a triangle. The three sides of the triangle represent three lines which could be represented by linear equations involving x and y. So the three points of intersection are a, b and c which evaluate to (4.330,-2.5), (-3.5,6.062), (-3.420,-9.397).