How are the three types of sedimentary rocks different in their formation?

you solve this by using this formula

7.75x + 153.95 + 7.75y + 129.02

so first you add what you can. in this case its 153.95 and 129.02

153.95 + 129.02 = 282.97

so we get

7.75x +282.97 + 7.75y

then you try to simplify the equation more

7.75x +282.97 + 7.75y

7.75(xy) + 282.97

your answer is 7.75(xy) + 282.97

this is your answer because no matter what number x and y are you still have to multiply them by 7.75.