How many ways can you arrange the numbers 1,3,5,7 to make a four digit number that uses each number exactly once

Yoku is putting on sunscreen. he uses 2\text{ ml}2 ml to cover 50\text{ cm}^250 cm 2 of his skin. he wants to know how many milliliters of sunscreen (c)(c) he needs to cover 325\text{ cm}^2325 cm 2 of his skin. how many milliliters of sunscreen does yoku need to cover 325 \text{ cm}^2325 cm 2 of his skin?

Solve this problem! extra ! 3025/5.5 = a/90.75 / = fraction

Present age of man is 45 years, 5 years back his age was 4 times age of his son what is present age of his son?