The rogers family drove a total of 482 miles, starting on
friday and ending on sunday. they drove 138 miles on friday and 225 miles on
saturday. how many miles did they drive on sunday?

you add up 138+225 and you get 363 then you subtract 482-363 this is how you set it up:

   4  8  2

- 3  6  3

you have to borrow because 3 does not go into 2 so you change the 8 into a 7 then you 10 to 2 and you get 12 so this is what it looks like:

     4   7   12

-    3   6   3

 so you then subtract 12-3=9 then 7-6=1 then 4-3=1

so this is what it looks like

    4     7    12

--- 3    6     3

    1     1     9

so on Sunday they rode 119 miles

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0