Answer:
x = x0 - 55*t, being 'x' the taxi's distance to San Diego, 'x0' the distance between Los Angeles and San Diego, and 't' the time in hours since the taxi left Los Angeles.
Step-by-step explanation:
Let's call the distance from Los Angeles to San Diego "x0"
The taxi is driving toward San Diego, so as time increases, its distance to San Diego decreases, so we need to use its speed with a negative sign in our equation of distance.
Being "t" the time in hours starting when the taxi leaves Los Angeles, and "x" the taxi's distance from San Diego in instant "t", we can formulate the equation:
x = x0 - 55*t
