A boy threw a ball upwards with an initial velocity of 3450 inches per second.?

You first have to convert the units to something uniform. Since you are using English units, the acceleration due to gravity is approximately 32 ft/s^2

Convert velocity to ft/s: V = (3450 in/s)(1 ft/12 in) = 287.5 ft/s

a)
V = Vo + at
V = 287.5 ft/s + (-32 ft/s^2)(2 s)
V = 223.5 ft/s

b)
Displacement:
Y = Yo + Voy t + (1/2)at^2
Y = 0 + (287.5)(2) + (1/2)(-32)(2)^2
Y = 511 ft

c)
Maximum height when V = 0
V = Vo + at
0 = (287.5 ft/s) + (-32)t
t = 8.98 seconds

d)
Maximum height:
Y = Yo + Vo t + (1/2)at^2
Y = 0 + (287.5)(8.98) + (1/2)(-32)(8.98)^2
Y = 1291.5 ft