Sam has 12 black and white photos and 18 color photos. he wants to put the photos in equal rows so each row has either black and white photos only or color photos only. in how many rows can sam arrange the photos?

He can arrange the black and white photes in 5 rows because you can make 2 rows of 6 or 6 rows of 2. also you can put 1 rows of 12 or 4 rows of 3 or 3 rows of 4. sam can arrange the color photes in 4 different ways of 18 because he can put 1 row of 18 or 18 rows of 1. Also he can put 2 rows of 9 or 9 rows of 2. 
Hope this helps!