How many 2 digit numbers can you write if you can use only the digits 1 and 2?

What is the difference between regular convex and concave polygons

The graph shows the decibel measure for sounds depending on how many times as intense they are as the threshold of sound. noise in a quiet room is 500 times as intense as the threshold of sound. what is the decibel measurement for the quiet room? 20 decibels28 decibels200 decibels280 decibels

In a rectangle klmn, km = 6x + 16 and ln = 49. find the value of x