The ratio of boys to the total number of students is 2:5. If there are 123 girls, how many boys are there? I estimated 49.2, is that correct?
Since there are 123 girls, that should be a ratio of 3:5.
123/3 = 41
41* 2 = 82
Check 123 + 82 = 205
82/205 = .4 = 2/5