Club a has 17 members and club b has 25 members. if there is a total of 38 people that belong to the two clubs, how many people belong to both clubs?

i know the answer and the steps required to solve it but i'm uncertain about why those steps are necessary.

The capulet and montague families love writing. last year, each capulet wrote 444 essays, each montague wrote 666 essays, and both families wrote 100100100 essays in total. this year, each capulet wrote 888 essays, each montague wrote 121212 essays, and both families wrote 200200200 essays in total. how many capulets and montagues are there? choose 1

How does reflecting or rotating a figure change the interior angles of the figure?

On the way home from visiting his family, vincent’s plane cruised at an altitude of 3.2 × 10^4 feet. he had heard that a man named felix baumgartner skydived from an altitude of 1.28 × 10^5 feet. vincent wants to know how much higher felix went on his skydiving trip. question 1 you have already seen how adding numbers works in either scientific notation or standard notation. but can you subtract numbers in scientific notation and get the same results as subtracting in standard notation? to find out, first solve vincent’s problem in standard notation. part a write the cruising altitude of vincent’s plane in standard notation.