A cross-country travels 20 kilometers before she realizes that she has to cover at least 75 kilometers in order to qualify for the next race. If the racer travels at a rate of 10 kilometers per hour, how many whole hours will it take her to reach the 75-kilometer mark?

It will be 7 hour and 30 min

So find how much the racer needs to cover more she covered 20 and needs to cover 75 75-20=55 she needs to cover 55 more so 10 km per hour 10 times x hours=55 miles divide both sides by 10 x hours=5.5 since you want whole hours, we round up so she at least gets there 6 hour, I think