On a farm, 4 1/2 out of every 15 acres of land are used to grow crops. wheat is grown on 5/8 of the land used to grow crops. what percentage of the total area of the land on the farm is used to grow wheat?

The answer is 18.75% (I THINK, I'm not very good at maths!) here's how I worked it out:

4.5 + 4 1/2 so for the first part it is a fraction 4.5/15 you then multiply this to 5/8 and get 225/120 which you can then simplify to 3/16 then you work out 3 divided by 16 and get 0.1875 and multiply this decimal by 100 to get the percentage, 18.75%. 

Hope this helped, but check with other people (I'm not very good at maths)!