Question

A family built a house in a beach resort area. In 1990, the house was 430 ft from the water. With erosion, the house was 400 ft from the water in 2000. In what year will the house be only 250 ft from the water?
a. 1990

c. 2015

b. 2004

d. 2050

Answer 1

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