<PRE><B>Question 302517</B>
let the base be x

altitude = x-5

Area of triangle = 1/2 * base * altitude

=1/2 *x*(x-5) = 42

x^2-5x=84

x^2-5x-84=0

x^2-12x+7x-84=0

x(x-12)+7(x-12)=0

(x-12)(x+7)=0

x=12 OR x=-7

So  the base is 12

Altitude = 12-5=7



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