In a class of 23 student the girls were 7 more than the boys how many boys were in the class

x=# of boys

x+7=# of girls

x+x+7=25

2x+7=25

2x=25-7

2x=18

x=18/2

x=9 boys

x+7=16 girls

If you don't understand variables use trial and error.

Boys     Girls

1           8

2           9

3           10

4           11

5           12

6           13

7           14

8           15

9           16   9+16=25 students

You could start this way...

Boys     Girls

12        13

11        14

10        15

9          16     16 is 7 more than 9