A cell phone plan is shown at the right. The rates, which include an unlimited data plan, are the same each month for 7 months. The total cost for all 7 months is 180.39. Let m represent the average number of minutes that exceeds 700 minutes each month

If you answer 2+2 you will get over 80 points

Prove (a) cosh2(x) − sinh2(x) = 1 and (b) 1 − tanh 2(x) = sech 2(x). solution (a) cosh2(x) − sinh2(x) = ex + e−x 2 2 − 2 = e2x + 2 + e−2x 4 − = 4 = . (b) we start with the identity proved in part (a): cosh2(x) − sinh2(x) = 1. if we divide both sides by cosh2(x), we get 1 − sinh2(x) cosh2(x) = 1 or 1 − tanh 2(x) = .

Oliver had $50 on the day before his birthday. after he recived some money for his birthday , he had $75. write and solve eqaution to find how much money oliver received for his birthday. x+50=75