Question 1109313
.
<U>1. Mental solution</U>.


<pre>
     8 x 5 inches.
</pre>

<U>2. Algebra solution</U>.


<pre>
    The condition gives you this equation

        x*(x+3) = 40.

        x^2 + 3x - 40 = 0.

    Now apply the quadratic formula or solve equation by factoring.


    On quadratic formula see the lessons

        <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/Introduction-Into-Quadratics.lesson>Introduction into Quadratic Equations</A>

        <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/proof-of-quadratic-by-completing-the-square.lesson>PROOF of quadratic formula by completing the square</A>

    in this site.
</pre>