When the US Air arena is filled up to 80% capacity, it holds 13,600 people. How many would it hold when completely filled?
ratio..
80%:13600 ppl
100%:17000 ppl
multiply 80 by 1.25 to make it 100, then multiply 13600 by 1.25 to get 17000.
You can also divide 13,600 by 80% (0.8), which will give you 17,000. Both methods use rules of solving ratios.