



 
Hi there. Start by assigning variables to what you want to know:
Since the question deals with area, let's also define a variable for the area and state the equation relating these variables:
Now translate the other two sentences into equations:
The general principle when working with systems of linear equations is that you need at least as many equations as variables in order to solve the system. Here, we have three variables: L, B, and A. And we have three equations:
Now use the substitution method (look that up in our Quick Search if you don't know how to do it) to substitute for A by blending equation i and iii. Then blend the result with ii by substituting for L. This will give you a singlevariable equation that you can solve for B. Using that value for B in equation ii, you can solve for L. Hope this helps,  


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