21/x = 55/100
this is how you would model this problem. now, multiply both sides by 100.
so 2100/x = 55. multiply both sides by x.
so 2100=55x
divide both sides by 55. so
x is 38.18181818 (18 repeating forever) so the number they are asking for is that 38.18 (18repeating forever). round as necessary