Carla has come across an example which has been used in her ecology textbook three different times. how should carla adjust her reading speed?

Given that Carla has already knowledge of the example from the Ecology textbook, then her reading will increase. It is called a prereading, it is a technique in which the reader will skim the text before reading it thoroughly. 

Carla already has an idea on what she will be ready since she has come across the example before reading the text carefully.