John is saving to buy a new car. His parents gave him $50 to start off. And he earned $20 per day working at the dairy farm. Write an equation that represents the situation given. What kind of math is this and how do I solve this?

Can someone me with my hwplz(only the circled ones)

Abus travels 36 miles in 45 minutes. enter the number of miles the bus travels in 60 minutes at this rate.

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.