In an intercollegiate competition that lasted for 3 days, 115 students took part on day 1, 80 on day 2 and 100 on day 3. If 50 took part on day 1 and day 2 and 70 took part on day 2 and day 3 and 40 took part on all three days, how many students took part only on day 3?  Choose the correct choice from the following options:
A) 20
B) 35
C) 40
D) 55
E) 60
Day 1&amp;2 = 50; Only Day 1&amp;2 (50-40) = 10,   Day 2&amp;3 = 70; Only Day 2&amp;3 (70-40) = 30,   Only Day 3 = 100 - (10+30+40)= 
<gadget id="calculator">100 - (10+30+40)</gadget>
<output>20</output>
20   20nswer:20
<result>A</result>
In an intercollegiate competition that lasted for 3 days, 115 students took part on day 1, 80 on day 2 and 100 on day 3. If 50 took part on day 1 and day 2 and 70 took part on day 2 and day 3 and 40 took part on all three days, how many students took part only on day 3?