Calculate area of room

Hey,Im an structure pupil. I need assistance with the calculation of space of the room. I perceive the formulation is size x width however after I did my calculation its not the identical as given within the e-book. Am I calculating unsuitable?

I need assistance with num 4,5 & 6

As for num 4, I attempted to divide the areas however the whole quantity is greater than the given num which is 37m2

As for num 5,I bought 66m2 space however the e-book mentioned 58m2

As for mum 6, I bought 48.7m2 however e-book mentioned 55.5m2

Its bizarre that generally after I calculate the realm of flats space within the commercial I all the time find yourself getting totally different numbers as effectively

Please assist me and let me know if I do one thing unsuitable,Im having a headache

https://preview.redd.it/91w87ppri5da1.jpg?width=4032&format=pjpg&auto=webp&s=99ca403d25d9b1965fe399ce6ef77dc604fbbd4e