The lens labelled (A) has radii 16.3cm and 11.6cm. Using the shape of the lens to assign the signs of the radii, calculate the focal length of the lens. Give your answer with the correct positive or negative sign using the usual convention for lenses.

Answermake them get very hot and over time wear them out;

So since the snail is moving at 3.6  miles per hour you multiply by 5280 to change it into feet per hour. so you get 36*528 ft per hour. since there are 3600 seconds in an hour, you divide 36*528 by 3600. so simplifying we get 528/100 which is 5.28 ft per second