Question

Yoku is putting on sunscreen. He uses

Answer 1

For this case we can make the following rule of three:
 2 ml -------------> 50cm ^ 2
 c -----------------> 325 cm ^ 2
 From here, we clear the value of c.
 We have then:
 c = (325/50) * (2)
 c = 13 ml
 Answer:
 I need 13 milliliters of sunscreen to cover his skin.