As a result of the 1998 tsunami in Northern New Guinea, 2200 people were killed. This represented 3/7 of the total number of people killed by tsunamis between January 1990 and January 2000. How many people were killed by tsunamis between 1990 and January 2000 (answer correct to 2 decimal places)
2200 = 3/7 Divide both sides by 3 -- carry the result to 3 decimal places, so that at the end you can round off to 2 places.
2200/3 = 1/7
Now multiply both sides by 7 to get the whole (7/7 = 1)
Round to 2 decimal places to finish.