w = white keys
b = black keys
w + b = 88
We know the number of black keys, it is 36
w + 36 = 88
w + 36 - 36 = 88 - 36
w = 52
So, the number of white keys is 52.
Now, we can write the ratio.
It would be :
b : w
36 : 52
Let's simplify . . .
They are both divisible by 4:
36/4 : 52/4
Simplifies to . . .
9 : 13
So, the ratio is 9 black keys: 13 white keys.
Final Answer: 9 black keys : 13 white keys
*I looked to see if this was actually true on a real piano, and it was!