Science
posted by Kate .
While picking up passengers in a big city, a taxi driver drives 20.0 blocks south, then 15.0 blocks east, and then 6.0 more blocks south. What is the magnitude of the taxi’s resultant displacement?
Iv'e been using the equation sqrt(x^2+y^2+z^2)
THe answer I get is 25.7, however, this is wrong. Please help!

why do you include a third dimension? The taxi cannot travel vertically.
The total displacements are
20+6=26 blocks south
15 blocks east.
So, √(15^2+26^2) = √901 = 30.0