There are 65 children in the sixth grade. If the boys and girls are in the ratio of 8:5, what equation should be used to find the common factor of boys to girls?

Select the correct response:
1.) 8x + 5y + 65 = 100

2.) 8x + 5y = 65

3.) 8x + 5x + 65 = 100

4.) 8x + 5x = 65