Answer: there are 20 girls in the club
Explanation:
Let b represent the number of boys in the school club.
Let g represent the number of girls in the school club.
The ratio of the number of boys to the number of girls in a certain school club is 3 to 4. This means that
3/4 = b/g
3g = 4b
b = 3g/4
If there are 5 more girls than boys in the club, it means that
g = b + 5 - - - - - - - - - - - 1
Substituting b = 3g/4 into equation 1, it becomes
g = 3g/4 + 5
Multiplying through by 4
4g = 3g + 20
4g - 3g = 20
g = 20
substituting g = 20 into b = g - 5, it becomes,
b = 20 - 5 = 15