Answer:
465
Step-by-step explanation:
Let the number of girls at the festival be--------- g
Let the number of boys at the festival be---------b
The conditions are;
2/7 g = 3/5 b ---------------(i)
g-b= 165 ---------------------(ii)---------make g the subject of the expression
g= 165 +b---------------------(iii)--------use this equation in (i)
2/7 (165 +b)= 3/5 b -------multiply both sides by 7
7*2/7(165+b) =3/5*7 b
2(165+b)=21/5 b ------multiply both sides by 5
5*2(165+b) = 21/5*5*b
10(165+b) = 21 b -------open brackets
1650 +10 b = 21 b------collect like terms
1650 = 21 b- 10 b
1650 = 11 b -----divide both sides by 11
1650/11 = 11b/11
150 = b = number of boys
Using equation (ii) where g-b =165 ; g-150 =165 , g= 165+150 =315 number of girls
Total number of children at the festival = 150+315 =465
