Answer:
There is no solution for either variable without further information, as there are two variables given, but only one relationship between them.
You could however use them as a description of a line, which gives every possible solution.
35x - 7y = 49
7y = 35x - 49
y = 5x - 7
We now have an expression describing a line with a slope of five, which crosses the y axis at (0, -7) and the x axis at (1.4, 0)
