A fruit shop brought in some fruit. A quarter of them were sold last week. This week another $120$ kilograms were sold. One third of the original fruit is left now. How many kilos of fruit did the fruit shop buy? 
Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Finding the Base
$$1-\frac{1}{4}-\frac{1}{3} =\frac{5}{12}$$, $$120\div\frac{5}{12}=288\text{kg}$$. 