Apiano has 52 white keys. write and use an equation to find the number of octaves (8 keys) on a piano keyboard.

Each octave in the piano is composed of 8 keys with the end key overlapping the next one which means the last key is the first key of the next octave. In 52 white keys, there are 7 octaves which is composed of 43 full keys and 7 overlapping keys. Answer to this problem is 7 octaves.

B + W = 88 
B = 7 *5 + 1 (5 black keys/8 keys per octave) 

therefore black keys = 36 and white keys = 52

Horizontal change or the change of x