A rollercoasterbrises 210 feet into the air, drops 240 feet, rises 80 feet before dropping another 30 feet again. Finally the rollercoaster drops another 50 feet. What is the height of the rollercoaster after the last drop

-30 feet

Step-by-step explanation:

What we know:

The rollercoaster first rose 210 feet, so after rise 1, the height is +210 feet.

After that, it dropped 240 feet. This is greater than the 210 feet it initially rose, so the number is now negative. The height is now -30 feet.

210 - 240 = -|240-210| = -|30| = -30 feet

After that, it rose another 80 feet. That outdoes the eariler -30 feet, so we're back to a positive height. After that rise, the height is now +50 feet.

-30 + 80 = |80 - 30| = |50| = 50 feet

Then the last two drops combine for a 80-foot drop. This is greater than the +50-foot height it was at, so we're back at -30 feet.

50 - 80 -|80 - 50| = -|30| = -30 feet after the last drop

the surface area is 124cm²

step-by-step explanation:

length: 4cm

width: 9cm

height:   2cm