How many white keys are there and use a ratio box to find the answer

Question

the ratio of white keys to black keys on a piano is 13 to 9.If there are 36 black keys hoiw many white keys are there?Use a ratio box to find the answer

Answer 1

13/9 = x/36

9x = 13*36

x = 36*13/9

x =  52 white keys