Answer: there were 14 boys and 7 girls in the class.
Explanation:
Let x represent the number of boys in the class.
Let y represent the number of girls in the class.
There were originally twice as many boys as girls in my honors geometry class. It means that
x = 2y
After three new girls join the class. the total number of students is 24. It means that
x + y + 3 = 24
x + y = 24 - 3
x + y = 21- - - - - - - - - - - -1
Substituting x = 2y into equation 1, it becomes
2y + y = 21
3y = 21
y = 21/3
y = 7
x = 2y = 2 × 7
x = 14