Standard form is x + y = number
y = 2/5 x - 6
y - 2/5 x = -6
-2/5 x + y = -6
In standard form, the coefficient of x cannot be negative and the coefficient of x and y cannot be a fraction.
Therefore we have to multiply the whole equation by -1 and then by 5.
-2/5 x + y = -6
2/5 - y = 6
2 - 5y = 30
