Consider the following premises. For all x_12, x_12 will make tea if and only if x_12 is a cashier. If it is late, then Linda is sad. If Linda were sad, then Mary is a cashier. Can we infer the following from them? If it is late, then Mary is making tea.
 From the fact that for all x_12, x_12 will make tea if and only if x_12 is a cashier we can infer that Mary is making tea if and only if Mary is a cashier. From the fact that if it is late, then Linda is sad, and that if Linda were sad, then Mary is a cashier we can infer that if it is late, then Mary is a cashier. From the fact that Mary is making tea if and only if Mary is a cashier we can infer that if Mary were a cashier, then Mary is making tea. Finally, from the fact that if it is late, then Mary is a cashier, and that if Mary were a cashier, then Mary is making tea we can infer that if it is late, then Mary is making tea. Therefore, the answer is yes.