I need some help with these

Malia is observing the velocity of a cyclist at different times. after two hours, the velocity of the cyclist is 15 km/h. after five hours, the velocity of the cyclist is 12 km/h. part a: write an equation in two variables in the standard form that can be used to describe the velocity of the cyclist at different times. show your work and define the variables used. (5 points) part b: how can you graph the equations obtained in part a for the first 12 hours? (5 points) if you can try and make this as little confusing as you can

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?