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
