Coincident equations have points on the line that may seem on top of each other.
x + 3y = 5
4x + _ y = _
Look at x. 1st equation, its coefficient is 1. 2nd equation its coefficient is 4. It is safe to conclude that the coefficient of the 1st equation is multiplied by 4.
so, 3y * 4 = 12y and 5 x 4 = 20
x + 3y = 5
4x + 12y = 20 to be coincident