There are many ways to solve number 5 as it is just an reduce/enlargement of equidistant fractions
The first method that came up to my mind is just dividing denominators.
For A) you can do 72 divided by 18 which would give you 4. Then you can divide the given numerator with the answer you got from dividing the denominators. This would be 8 divided by 4 which would give you two. This means that 2/18 is equal to 8/72. You can check by simplifying the fraction. Both 2/18 and 8/72 equal 9 when simplified, therefore correct.
You can use this method for b, either use a calculator because of the decimals or just remove the decimals and replace them later. Make sure when you use this method, you are always dividing the bigger number. So in B you would do 40.3 divided by 12.4
