About Iran&Iranian-No.1

We are almost 75 million. ( We have almost 75 million people). 
We have one common accent and dialect that if the Iranian people want to speak together should talk on it, example the Scottish and Irish and British, If they want to speak to each other should speak on standard accent! ( If they want to speak to eachother, they should speak plain English )
Our capital is Tehran the most populous ( city) and ( it has ) the best facilities in (the)whole of Iran.
The best university, school, hospital, Amusement, restaurant and fast food, etc (are) 

in Tehran.
There are expensive cars in cities particularly in Tehran.
We have got  ( a disproportionate) income level ( In Iran ), as some people can’t afford  food for their dinner ( while others ) can have the most expensive foods, cars, houses, etc.
Iran and especially Tehran is most expensive for ourselves. The majority of incomes are very low and expenses are really high!
We have the best carpets in the world.
We like painting!
We have got  great ancient monuments in several cities for example Isfahan, Yazd, Kashan, Kerman, etc.
We like the foreign people.
All the best.

Not sure if my corrections are what you intended to say but very well done! As a native English speaker I understood what you meant. Well done on the difference between "their" and "there", some English speakers can't even use them correctly. Also the use of "etc" makes you sound more native. Keep up the hard work! 

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