What is the area of a triangle whose base is 15 centimeters and whose height is 10 centimeters?

im having trouble understanding, explanation would be great thx : )

Adecibel is a logarithmic unit that can be used to measure the intensity of a sound. the function y = 10logx gives the intensity of a sound in decibels, where x is the ratio of the intensity of the sound to a reference intensity. the reference intensity is generally set at the threshold of hearing. use the graphing utility to graph the decibel function.a whisper has a sound intensity of 30 decibels. use your graph to you complete the following statement. the sound intensity of a whisper is times the reference intensity.

Which of the following parabolas opens down?

I’m really confused and need to learn this