How do i find the length to the indicated segment?

The two-way table shows the number of people whose hobbies are reading or solving puzzles and who either ride a motorcycle or don’t ride a motorcycle. among people whose hobby is reading, what is the relative frequency of not riding a motorcycle? express your answer as a decimal, and round it to the nearest hundredth if necessary. enter your answer in the box. reading solving puzzles ride a motorcycle 7 3 don't ride a motorcycle 5 9

Determine the difference: 3.2 × 1010 – 1.1 × 1010. write your answer in scientific notation.

Sum is 17 and their difference is 3