Task: Question Answering
Input (English): Problem: jack and christina are standing 150 feet apart on a level surface . their dog , lindy , is standing next to christina . at the same time , they all begin moving toward each other . jack walks in a straight line toward christina at a constant speed of 7 feet per second and christina walks in a straight line toward jack at a constant speed of 8 feet per second . lindy runs at a constant speed of 10 feet per second from christina to jack , back to christina , back to jack , and so forth . what is the total distance , in feet , that lindy has traveled when the three meet at one place ? 
Options: a ) 40 , b ) 60 , c ) 80 , d ) 100 , e ) 120
Output (English): d