Can someone help me with this please

Asequence is defined recursively using the formula f(n + 1) =f(n) - 5. which sequence could be

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?

Alex measured the length of an item to be 3.7 cm. the actual length is 3.5 cm. what is alex’s percent error?