Help please!

Question 5 161 Write the following arguments in symbolic form. Then establish the validity of the argument by providing a proof, or give a counterexample to show that it is invalid: (a) If Rochelle gets the supervisor's position and works hard, then she'll get a raise. If she gets the raise, then she'll buy a new car. She has not purchased a new car. Therefore either Rochelle did not get the supervisor's position or she did not work hard. (b) If there is a chance of rain or she is not wearing her red headband, Lois will not mow her lawn. Unless the temperature is less than 28 degrees, there is no chance of rain. Today the temperature is 30 degrees and Lois is wearing her red headband. Therefore (sometime today) Lois will mow her lawn Question 5 161 Write the following arguments in symbolic form. Then establish the validity of the argument by providing a proof, or give a counterexample to show that it is invalid: (a) If Rochelle gets the supervisor's position and works hard, then she'll get a raise. If she gets the raise, then she'll buy a new car. She has not purchased a new car. Therefore either Rochelle did not get the supervisor's position or she did not work hard. (b) If there is a chance of rain or she is not wearing her red headband, Lois will not mow her lawn. Unless the temperature is less than 28 degrees, there is no chance of rain. Today the temperature is 30 degrees and Lois is wearing her red headband. Therefore (sometime today) Lois will mow her lawn