help with chi square tests in excel

[nuSFwck]

i'm having a problem figuring out some functions on excel. for some homework problems, i have to do some chi-square tests of independence.

here is what i know:
the critical chi-square value is found by "=CHIINV(level of significance, degrees freedom)"

i need to to figure out how to calculate the computed chi square value so i can draw conclusions about brand dependence for a certain problem. what commands/formulas do i need to do in excel to generate this value?

here is a picture of the information i need to use (this may or may not be helpful):
excel picture