We develop an equation for the given situation by first writing the general equation for lines,
y = mx + b
Substituting to this given the values given above,
(1990) 430 = b
(2000) 400 = m(10) + 430
The value of m from the equation in 2000 is -3. Thus, the equation of that relates the variables is,
y = -3x + 430
Answer:

Step-by-step explanation:
Given
-- of the roadworks

Required
Determine the speed
In this case:


<em></em>
<em> --- approximated</em>