the beggining number is 0
Boys have to add up their numbers to counter girls -2,-4,-6,-8,-10,-12,-14 and so on.
Girls have to add up their number to counter and add up till they get to +100
by adding up with the same concept as boys exept they are positif(+) and boys are negatif(-)
Boy
-2
Boy2
-4
Girl
-2
Boy3
-4
Boy2
-6
Girl2
-4
Girl3
-2
Girl2
0
Girl
2
and so on