When chasing a hare along a flat stretch of ground, a greyhound leaps into the air at a speed of , at an angle of above the horizontal. (a) what is the range of his leap and (b) for how much time is he in the air?

The equations for this projectile motion is written in the picture attached.

a.) For this part, you use the last equation. In here, you will need the initial velocity and the launch angle. There seems to be missing information about that. Let's just suppose that the initial velocity is 5 m/s and the launch angle is 30° above the horizontal.

R = (5 m/s)²(sin2*30°)/9.81 m/s² = 2.207 m

b.) You use the first equation for this part.

t = 2(5 m/s)(sin 30°)/9.81 m/s² = 0.51 seconds

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current