Answer:
The dimensions are:
by 
Step-by-step explanation:
The area of the rectangle is given as

The factored form of this quadratic trinomial gives the dimensions of the rectangle.
We factor 3 first to obtain;

We split the middle term to get;

We factor within the parenthesis to get;

We factor further to get;

The dimensions are:
by 
Then the perimeter will be

In your question that ask to calculate the area of one of the tiles if a semicircular archway in the front of the garden is using 8 congruent granite tiles and the area of one of the tiles is 2.9ft ^2. I hope you are satisfied with my answer and feel free to ask for more.
X=2
2x-3=-x+3
add three to both sides
add 1x to each side
should be left with 3x=6
divide both sides by 3 to get x alone
your answer then is x=2