What is equivalent to 18/4

What is the number 321,000,000 in scientific notation? also what is the number? ?

The acceleration of an object due to gravity is 32 feet per second squared.what is acceleration due to gravity in inches per second squared?

Every weekday, mr. jones bikes from his home to his job. sometimes he rides along two roads, the long route that is shown by the solid lines. other times, he takes the shortcut shown by the dashed line. how many fewer kilometers does mr. jones bike when he takes the shortcut instead of the long route?