Respuesta :

21 + 13 = 34 with a difference of 8
[tex]\bf \begin{cases} b+h=34\\ b-h=8\to \boxed{b}=8+h\\ --------------\\ b+h=34\iff \boxed{8+h}+h=34\implies h=? \end{cases}[/tex]

solve for "h", to see what "h" is

what about "b"?  well,  b = 8+h

once you've found both, what's their product? or b*h?