Chapter 7.1, Problem 8PP

Aluminum sulfate,
   $A{l}_2{\left(S{O}_4\right)}_3$ , is used in some antiperspirants.
a. How many moles of O are present in 3.0 mol of $A{l}_2{\left(S{O}_4\right)}_3$ ?
b. How many moles of aluminum ions $\left(A{l}^{3+}\right)$ are present in 0.40 mol of $A{l}_2{\left(S{O}_4\right)}_3$ ?
c. How many moles of sulfate ions $\left(S{O}_4^2\right)$ are present in 1.5 mol of w $A{l}_2{\left(S{O}_4\right)}_3$ ?