maria has 15 fewer apps on her phone than orlando. if the total number of apps on both phones is 29, how many apps are on each phone

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?

Could somebody me with this radical simplification?

Extra points! find the missing dimension! need asap