a ’ s speed is 20 / 13 times that of b. if a and b run a race, what part of the length of the race should a give b as a head start, so that the race ends in a dead heat?	Choose the correct option
A) 1 / 17
B) 3 / 17
C) 1 / 10
D) 7 / 20
E) 3 / 10
<gadget id="calculator">20 - 13</gadget>
<output>7</output>

<gadget id="calculator">7 / 20</gadget>
<output>7/20 = around 0.35</output>

<result>D</result>
a ’ s speed is 20 / 13 times that of b. if a and b run a race, what part of the length of the race should a give b as a head start, so that the race ends in a dead heat?
divide(subtract(20, 13), 20)
"we have the ratio of a ’ s speed and b ’ s speed . this means , we know how much distance a covers compared with b in the same time . this is what the beginning of the race will look like : ( start ) a _________ b ______________________________ if a covers 20 meters , b covers 13 meters in that time . so if the race is 20 meters long , when a reaches the finish line , b would be 7 meters behind him . if we want the race to end in a dead heat , we want b to be at the finish line too at the same time . this means b should get a head start of 7 meters so that he doesn ’ t need to cover that . in that case , the time required by a ( to cover 20 meters ) would be the same as the time required by b ( to cover 13 meters ) to reach the finish line . so b should get a head start of 7 / 20 th of the race . answer ( d )"