In 1979, a river was #27# feet below a bridge. By 1989 it was only #18# feet below. Assuming the rate of rise is constant, write an expression for the distance from the bridge to the river. In what year will the river reach the height of the bridge?
The answer is
We are starting, at
From there, we discover that the level changed by
That means that the rate of rise is
To find the year in which the river reaches the bridge, we know that the distance between them will be
Solving this gives