Devide 33 to get a ratio of 4 to 7

33 photos in a 4x to 7x ratio

4x + 7x = 33

11x = 33

x = 3

33 photos can be put in a 4 (3) to 7 (3) ratio

which is a 12 to 21 ratio

so 12 photos on one side, and 21 on the other side to get the ratio of 4 to 7

Note:

a (b) = ab = a x b = a times b