Find the common difference -7x,-4x,-x,2x

Can someone me and explain..will award brainlest!

There are 2 ones, 1 five,3tens, and 1 twenty. if there are 28 bills in her wallet, what would you predict is the approximate value of all the bills

The thickness of photoresist applied to wafers in semiconductor manufacturing at a particular location on the wafer is uniformly distributed between 0.2070 and 0.2171 micrometers.(a) determine the proportion of wafers that exceeds 0.2125 micrometers of photoresist thickness. (round your answer to 3 decimal places.)enter your answer in accordance to the item a) of the question statement(b) determine the mean of x. (round your answer to 4 decimal places.)enter your answer in accordance to the item b) of the question statement micrometers(c) determine the variance of x. (round your answer to 8 decimal places.)enter your answer in accordance to the item c) of the question statement micrometers2