Alex bought a quarter of both the types of muffins. How many muffins did he buy in total?

There are eight yellow muffins, so a quarter of yellow muffins =8 ÷ 2 = 4 muffins
There are 12 pink muffins so a quarter of pink muffins = 12 ÷ 4 = 3
Total number of muffins purchased by Alex = 2 + 3 = 5