10 college students of team X took part in a Mathematics quiz. If the number of ladies is four more than the number of boys, then find the number of boys who took part in the quiz.

No. of boys = x 

and No. of ladies = y 

According to the given conditions:

x + y =10      ...(i)

and y = x + 4     ...(ii)

By solving equation 1 and 2 we get,

x + x + 4 = 10

2x + 4 = 10

2x = 6

x = 3 

and y = x + 4

y = 7 

⇒ Number of boys = 3​