57. If you draw a diagram and make a right traveler with the Jacques, the base of the cliff, and the top of the cliff, it should be obvious that tan(35 degrees) = (cliff height)/1200m. Solving, cliff height = 1200 * tan(35 deg) = 840 meters.
59.
Original price = 480
After 20% off, price = 480 - 0.20 * 480 = 384
After 7.5% tax, price = 384 + 0.075 * 384 = 412.80, which is the total desired.