You know 2 points which are [as you are told it passes x-axis through which occurs when ] and .
An equation of a straight line is in the form: where and are your variables, is your gradient and is your y-intercept.
Gradient is calculated by where and are two co-ordinates.
Use this gradient value and any co-ordinates to find the general form of the equation using where are any co-ordinates of the line.
The method and working out:
The two co-ordinates are and .
Check this with the other co-ordinates, .
Therefore the equation of the line is .