Translation:Wash your hands before eating the strawberry cake.
yes you can but little bit different.
technically, 씻으세요(-하세요) is a imperactices.
씻어주세요(-해주세요) is a much more polite expression.
~으세요 should probably be translated as "Please ~". It's kind of hard to translate imperatives in Korean because there are 3 basic levels whereas English just has 2 basic levels. 이거 해. Do this. (Impolite command) 이거 하세요. (Please) do this. (Polite command) 이거 해주세요. Please do this. Please do me a favor and do this. (Polite request) It really depends on context whether a ~으세요 command should be translated with 'please' or not. It wouldn't be correct to teach an English speaker that they all translate to not saying please (which can be rude in some contexts) and therefore the lowest level of politeness. If you look at the common contexts in which ~으세요 commands are used it maps much better on to "Please do" than just "Do". Please exit on the right. Please only take one. Please be quiet in the library. These are not commands that would use ~주세요 but just ~으세요.
It should be accepted and is even closer to the original word order. It needs a comma, but Duolingo doesn't recognize punctuation and capitalization errors.
Since no part of a Korean meal is traditionally eaten by hand, it seems many Koreans might not have the habit of washing their hands before eating. On the other hand, there are restaurants in Korea where customers have to take off their shoes at the door. Blowing one's nose in front of other people is also considered impolite, so it's probably best to go to the bathroom for that.
do you mean people only have the habit of washing their hands before a meal if they use cutlery? i think it depends on the person only. i rarely use my hands while eating but i can't sit down to eat calmly while not having washed my hands