I really need help with this, please answer all parts and you will get a brainy!

What is the 12th term of b(n)=-4-2(n-1)

What is the mean of the data set 125, 141, 213, 155, 281

20 points for the answer. this is for real , don't put random ! a rectangle has a length of 4 centimeters and a width of 7 centimeters. what is the effect on the perimeter when the dimensions are multiplied by 5? the perimeter is increased by a factor of 5. the perimeter is increased by a factor of 20. the perimeter is increased by a factor of 25. the perimeter is increased by a factor of 100.