You're supposed to simplify these, but for the last one, isn't it simplified enough?

Which expression is equivalent to (3^2)^-2 a.-81 b.-12 c.1/81 d.1/12

Find the least common denominator for thesetvo rational expressions.n^2/n^2+4n+4 -3/n^2+7n+10

If mary had 320 toy cars and she gave her friend 50 cars and then she gave her brother 72 more cars how much toy cars would mary have left ● explain with proper details