$v_{ox} = 150 \cos 56^\circ = 83.88 ~ \text{m/sec}$
$v_{oy} = 150 \sin 56^\circ = 124.36 ~ \text{m/sec}$
$y_{max} = \dfrac{{v_{oy}}^2}{2g} = \dfrac{124.36^2}{2(9.81)}$
$y_{max} = 788.19 ~ \text{m}$
$H_{max} = 120 + y_{max} = 120 + 788.19$
$H_{max} = 908.19 ~ \text{m}$ answer
$y = v_{oy}t - \frac{1}{2}gt^2$
$-120 = 124.36t - \frac{1}{2}(9.81)t^2$
$4.905t^2 - 124.36t - 120 = 0$
$t = 26.284 ~ \text{sec}$ answer
$v_{Gx} = v_{ox} = 83.88 ~ \text{m/sec}$
$v_{Gy}^2 = v_{oy}^2 - 2gy$
$v_{Gy}^2 = 124.36^2 - 2(9.81)(-120)$
$v_{Gy} = 133.49 ~ \text{m/sec}$
$v_G = \sqrt{{v_{Gx}}^2 + {v_{Gy}}^2} = \sqrt{83.88^2 + 133.49^2}$
$v_G = 157.656 ~ \text{m/sec}$ answer
