Here is a picture with the answer.
Notice the picture below, see the length "l"?
well

solve for "w", to find the width,
what's the length? well, l = 11/4 w
Answer:
50 1/3
Step-by-step explanation:
(40+x)/2=60
40 +x = 120
x = 80
check :
40+80 = 120
120/2 = 60
so his second round needs to be 80 mph