# Linear Function

Volumes:   Simple Math

Very common problem in computational programming is to determine the underlying law to which some phenomenon obeys. For learning purpose let us practice a simple variant - discovering linear dependence by two given observations (for example, how the price for some product depends on its size, weight etc.)

Linear function is defined by an equation:

``````y(x) = ax + b
``````

Where `a` and `b` are some constants.
For example, with `a=3, b=2` function will yield values `y = 2, 5, 8, 11...`
for `x = 0, 1, 2, 3...`

Your task is to determine `a` and `b` by two points, belonging to the function.
I.e. you are told two pairs of values `(x1, y1), (x2, y2)` which satisfy the function equation - and you should restore the equation itself.

Test data contains number of test-cases in the first line and then test-cases themselves in separate lines. Each case contains 4 integer numbers. Results should be integer too and you are to write them in line, separating with spaces and enclosing each pair in parenthesis, for example:

``````input data:
2
0 0 1 1
1 0 0 1