What is the difference between 12 feet and -12 inches?

Two cyclists 84 miles apart start riding toward each other at the samen time. one cycles 2 times as fast as the other. if they meet 4 hours later what is the speed (in miles) of the faster cyclists

If you are trying to move an attached term across the equal sign (=), what operation would you use to move it?

The area of a circle is equal to 1 dm². find the radius of the circle.