Mark has less than 35 stickers. When he packs the stickers in groups of 6, he will have 5 extra stickers. When he packs the stickers in groups of 5, he will have 4 extra stickers. How many stickers does Mark have?

6a + 5 = x

5b + 4 = x
6a + 5 = 5b + 4
when a = 4, b = 5
6a + 5 = 6 * 4 + 5 = 24 + 5 = 29
5b + 4 = 5 * 5 + 4 = 25 + 4 = 29
6a + 5 = 5b + 4
so, x = 29