Related rates problem

Find the rate of change of the area of A when h=3, if h is decreasing at a rate of 0.5 units/sec. Write answer in simplified fraction or expression.

Next, chad created this graph with ordered pairs that show the possible ratios of the number of damage to defense cards in his deck.what error chad make?

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

Which of the expressions (on the photo document i inserted) together represent all solutions to the following equation? 8cos(12x)+4=-4 *the answer should be in degrees.* > i would like for someone to explain the process to find the solutions for this.