Lily's tomato plant grew 3.5 cm in one week. what is this number rounded to the nearest cm?

3.5
cm would be the first whole number.
So if the number after the whole number (the tenth) is 0-4 the whole number doest change. If it's 5-9 you add one to the whole number.
Since it is a 5 you add one to the 3 making it 4 :)

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0

the value of x is equal to 0.