At noon, a tank contained 8 cm of water. after several hours, it contained 4 cm of water. what is the percent decrease of water in the tank?

50%

Step-by-step explanation:

The water decreased by 50% because the water started at 8 cm and went down to 4 cm. Half of 8 is 4, or if you multiply 8 by .5, or 50%, you get 4.

the sum of all the angles in a triangle are equal to 180

so you can add   the 3 given angles together to equal 180:

5y + 2y + 2y = 180

or since all three angles have the same letter, combine the 3 angles to equal 180:

9y = 180