Respuesta :

1/2 × (h + 1) × 6 = 18 [multiply 1/2 and 6, then divide my 18]
(h + 1) = 6 [subtract 1 from 6]
h = 5

Now seeing if it's correct; 1/2 × (5 + 1) × 6 = 18

Hope this helped! :)
[tex]\boxed{A= \frac{leg_1 \times leg_2}{2} } \\ \\ 18= \frac{6 \times (h+1)}{2} \\ \\ 18=3 \times (h+1) \\ \\ 18=3h + 3 \\ 3h=18-3 \\ 3h=15 \\ \boxed{h=5} [/tex]