x= axis

y= axis

u= upwards direction

t = time between rooftops

Initial velocity uy = 5.0 sin(15 deg) = 1.29 m/s
Acceleration = -g (downward pull of gravity) = -9.8 m/s^2
Displacement Y = -2.5 m (negative because other roof is below the first roof)
Let vy = final velocity in y direction

vy^2 = uy^2 - 2gY
Or vy^2 = 1.29^2 - 2*9.8*(-2.5)
Or vy^2 = 1.6641 + 49
Or vy^2 = 50.6641
vy = - sqrt(50.6641)
Or vy = -7.12 m/s
Average velocity in y direction = vyavg = (vy + uy)/2
= (-7.12 + 1.29)/2
= -5.83/2
= -2.915 m/s
Time taken t = Y/vyavg
Or t = (-2.5)/(-2.915)
Or t = 0.858 s

Horizontal component of velocity vx = 5.0 cos(15 deg) = 4.83 m/s
vx is constant because there is no force in X direction.
X = displacement in time t
X = vx * t
Or X = 4.83 * 0.858
Or X = 4.14 m
4.14 > 4.0

He should be able to make the jump.