The grasshopper, the frog and the mouse had a jumping contest. The grasshopper jumped w inches. The grasshopper jumped x inches farther than the frog and the mouse jumped y inches lesser than the frog. How much farther did the grasshopper jump than the mouse?
The grasshopper jumped 21 inches. 
The frog jumped 21 + 16 = 37 inches. 
The mouse jumped 21 - 25 = -4 inches. 

The grasshopper jumped 21 + 25 = 46 inches farther than the mouse.