⇒To get the slope it requires us to have two points
⇒you can take any two points of your choice
I will take (1,5) and (2,10)
⇒To calculate the slope of the line we use the formula

where m is the variable that represent the slope of the line.
Let us substitute the points and simplify to get the slope.
⇒

⇒The gradient of the line is equal to 5
⇒ the general equation of finding the equation of a straight line is y=mx+c
where y is the y coordinate,
x is the x coordinate
and c is the y-intercept that you want in this case.
⇒To get it in the place of x and y in the general equation choose any point of your choice and plug it in.
⇒You already have the known variable m which is the slope in this case equal to 5.
⇒You can plug in any point of your choice in the picture as you would still get the same value of the y-intercept represented by letter c in the equation.
⇒I will use the point (2,10) in the place of (x,y)

⇒As indicated in the calculation the y intercept is 0 as c=0
⇒Now for the equation according to the values we find previously m=5
c=0
∴ the equation of this straight line is y=5x+0
simply because 0 has no effect ∴ y=5x