I am struggling to answer this problem. Chapter 6 of Crossing the River with Dogs Ver.3, I am on problem 13 of page 168. We are supposed to be using the Guess and Check method, but I don't really understand how to just guess.

VOMEN'S WORLD CUP SOCCER Imagine that you traveled back in time to the Fourth of July, 1999. Yoru are at Stanford Stadium, watching the semifinal of the Women's World Cup soccer match. Mia Hamm, star of the United States team, has just received the ball on a breakaway. She is 60 yards from Brazil's goal. Brazilian star Sissi is the closest opponent to Hamm and is 10 yards behind her. Mia takes off for Brazil's goal and, while dribbling the ball, is able to run at a speed of 6.8 yards per second. Sissi takes off at the same time as Hamm and runs at 8.4 yards per second. (She is able to run faster because she isn't dribbling the soccer ball.) Hamm has decided to shoot at the exact moment that Sissi catches up to he because at that point it will still be difficult for Sissi to block the shot when she is side by side with Hamm. How far away from the goal will Hamm be when she shoots?