Anyone has any to do this question?

Tom can paint the fence in 12 hours, but if he works together with a friend they can finish the job in 8 hours. how long would it take for his friend to paint this fence alone?

I’m still confused on how to work the percentages

Alina fully simplifies this polynomial and then writes it in standard form. xy2 – 2x2y + 3y3 – 6x2y + 4xy2 if alina wrote the last term as 3y3, which must be the first term of her polynomial in standard form? xy2 5xy2 –8x2y –2x2y