When you are looking for a fraction, it is best to convert this into a percentage, which in this case, is 80%. Following on from this, you will have to round the number up, which in this case, will be to 200- however, depending on the number, this could be different. From this, you then have to find 80% of 200. From this, you then have to divide 200 by 10, giving you 20, and then multiply this by 8, to get 160, and this is a good estimate for 4/5 of 192. Hope this helps you