There has to be something in between the two numbers, for example 7 x 7 or 7+7 not just 7 7. Without the equation it would be highly impossible to answer :D
To convert from rectangular coordinate (x, y) to polar coordinate (r, θ).
r is given by the square root of the sum of the squares of the rectangular coordinate.

and θ is given by the arctan of the ratio of y to x.

Example:
To convert rectangular coordinate (3, 4) to polar coordinate

Therefore, rectangular coordinate (3, 4) = polar coordinate (5, 53.13°)
Here's a picture to explain it better.
A+b+8 = 11-3c
a+b+3c = 11-8
a+b+3c = 3
a = b-1
c = b+1
b-1+b+3*(b+1) = 3
2b-b+3b+3 = 3
4b = 3-3
4b = 0
b = 0
a = b-1
a = 0-1
a = -1
c = b+1
c = 0+1
c = 1
a = -1, b = 0, c = 1