Any tips on how to do this?? i have no clue how

Sherina wrote and solved the equation. x-56=230 x-56-56=230-56 x=174 what was sherina’s error? sherina’s work is correct. sherina only needed to subtract 56 from 230. sherina made a subtraction error when subtracting 56 from 230. sherina should have added 56 to both sides of the equation.

30 in the diagram line e and made parallel to each other and line p and q are transversal. use properties of special angles formed by parallel lines and their transversals to find the missing angle measures. m< 3=65 m< 15=120 m< 7= m< 4= m< 6= m< 1= m< 16= m< 18= m< 21= m< 10= m< 11= m< 12=

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.