Question 1091972
<br>I find it easier in nearly all cases to solve a problem like this using a single variable instead of two.<br>
So I would say
let x = number in second group
then 2x-4 = number in first group<br>
Then since the total number of students is 77,
{{{x + 2x-4 = 77}}}<br>
And it should be easy to solve from there....