The scatter plot shows the number of animal cells clara examined in a laboratory in different months:
plot ordered pairs 1, 20 and 2, 60 and 3,100 and 4, 140 and 5, 180
what is the approximate predicted number of animal cells clara examined in the 9th month?

Time is always the independent variable (given that there exists a time in the given data). Since time is the independent variable, the other data is the dependent variable (calories). Plotting it, independent variable is always the x-axis. X-axis is the horizontal axis in the coordinate plane.