On a recent trip, Juan started at an elevation of 1200 feet above sea level. He descended into a valley 20.4 feet below sea level. Which of the following shows one way to calculate how many feet he descended in all? A. -20.4 – (-1200)
B. 1200 – 20.4
C. -20.4 + 1600
D. 1200 – (-20.4)

Solve the system of equations y= 3/2 - 1, -x+ y =-3

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) = .

Kyle and elijah are planning a road trip to california. their car travels 3/4 of a mile per min. if they did not stop driving, how many miles could kyle and elijah drove in a whole day? ? 1 day = 24 hours. plzzz write a proportion i will give you 100 points