Question

The teacher separated her class of twenty-eight student into two group. one group has 4 more than twice as many students as the other group. how many students are in each group?

Answer 1

x+y=28
x=28-y

x=4+2y
28-y=4+2y
28-4=2y+y
24=3y
24/3=y
y=8
x+y=28
x+(8)=28
x=28-8
x=20
(20)=4+2(8)
20=4+16
20=20
one group=20, other group=8

Answer 2

You can use a system of equations.
x=group 1
y=group 2

x+y=28
2x+4=y

Isolate the variable in equation 1.

y=-x+28

Substitute it into equation 2.
-x+28=2x+4

Solve.
-3x=-24
x=8

Substitute it into one of the equations for y.
-x+28=y
-8+28=y
y=20

There are 8 students in one group and 20 students in the other.

Hope this helps!