In an action-adventure film, the hero is supposed to throw a grenade from his car, which is going 99.0 km/h , to his enemy's car, which is going 124 km/h . the enemy's car is 16.9 m in front of the hero's when he lets go of the grenade.

First thing to do is to uniform all units needed in the problem. 90 km/h is equal to 25 m/s while 110 km/h is equal to 30.5 m/s. The difference between the two is the reference of the car of the enermy which is equal to 5. 5 m/s.
Since the grenade follows a projectile motion, x or the range of teh shot is equal to v cos theta t where theta is equal to 45 degrees. 
The y-components are expressed as followsy = v sin 45 t - gt^2 where g is 9.8 m/s2v = v sin 45 - gtIn the enemy's side: we wirtex = 15.8 + 5.5 twhere 15.8 is the initial difference in distance between them.

we equate y to zero to actuate the same moment the grenade is thrown upwards0 = v sin 45 t - 9.8 t2v cos45 t = 15.8 + 5.5 tt = 0.144v v by substitution is equal to 17 m/s
x component of this velocity is 17 cos 45  + 25 equal to 37 m/sThe magnitude thus of the velocity by Pythagorean theorem is equal to 39 m/s

The charge of an ion with 55 protons and 52 electrons is +3. the reason is because protons are positive, and there are three more than the amount of negative electrons.

If its history of, then b) because a) implies only present day (now)