9s plus 3=57 pls help me

Your ultimate goal is to get the variable secluded all by itself.  You'll have to use the opposite operation to do this and remember, what you do to one side, you have to do to the other.
1. 9s + 3 = 57
2. Subtract 3 from each side. This will result in 9s = 54
3.  To undo the multiplication of 9s you'll divide both sides by 9.  9s/9 = 54/9
4.  The ending result is: s=6
5.  Go back and check your work by substituting it in your original equation.

You can find the area of a rectangle by multiplying the length and height. so multiply 1/2*7/4(which is the simpler version of 1 3/4) and you get 7/8 as your answer.