1- The city has spent a big (large)* amount of money on crime prevention.
2- A number of cities haVE* more than ten million inhabitants.
3- A large proportion of people commute to work by car.
4- The major cities have a high* level of unemployment.
5- A number of surveys haVE* been carried out.
6- Only a small percentage of the houses haVE electricity.
7- The number of private cars is increasing rapidly.
8- People are now enjoying a higher level (standard)* of living.
9- The food supply is not proportional* to the size of the country.
10- Compared to other countries, Libya (Libyans?) spends a high percentage of income on education.* I don't know if they are talking about the people of Libya, or the government. If it is Libyans, 'spend' should not be pluralized.
I put in brackets the more commonly used words.