The table shows numbers with the ratio x : y. Find the missing number.

x 4? 36 42

y 20 120 180 210

This is the concept of functions. Given the table that shows the numbers with ratio x:y. To find the missing number we proceed as follows;

x: 4,_,36,42

y:20,120,180,210

Getting the ratios of each corresponding values we get:

4:20=1:5

36:180=1:5

42:210=1:5

therefore the common ratio is 5. Hence the missing value will be:

120/5=24

The missing number is therefore 24