Can some please help me?! which polynomials are in standard form? choose all answers that apply: .10-n .5n+3n^3-1 .n+4n^2-7n^3 .none of the above

The sum of the speeds of two trains is 720.2 mph. if the speed of the first train is 7.8 mph faster than the second train, find the speeds of each.

Someone me! will award brainliest if u explain and answer!

What will be the end result for the taxpayer who filed his federal income tax return using the 1040ez form shown belowa he'll owe $173b he'll receive a refund of $173c he'll owe $3921d he'll receive a refund of $3921