[tex]b = h - 1[/tex]
[tex]A = \frac 1 2 b h = \frac 1 2 (h-1) h[/tex]
[tex]15 = \frac 1 2 (h-1)(h)[/tex]
[tex]30 = h^2 - h[/tex]
[tex] h^2 - h - 30 =0 [/tex]
[tex](h-6)(h+5)=0[/tex]
[tex]h=6 \textrm{ or } h=-5[/tex]
We can reject the negative height
Answer: 6 meters, second choice
