3x - 20y = 36
multiply through by the lowest common multiple of 3 and 4, that is 12
20y = 3x - 36
subtract 3x from both sides
- 3x + 20y = - 36
In standard form the coefficient of x must be a positive integer.
multiply all terms by ( - 1)
3x - 20y = 36 ' in standard form '