If each dimension of a rectangle decreases by 1, its area will decrease from 2017 to 1917. What will be the area of the rectangle if each of its dimensions increases by 1?
+118609 let the dimensions be x and y DRAW PICTURES OF THE RECTANGLES
x * y = ?
decrease each of the sides by 1. Now we know that
(x-1)(y-1) = ?
expand this and work out the value of x+y
If you increase the sides by 1 then you have an area of (x+1)(y+1)
expand this then substitute the known values.
Now you have your answer.
Give it a go and get back with what you have done. 
