When the function goes 1 to the right, it goes 2 down. Therefore the direction of the function is

Hence, the function represented is
y = -2x
A number b increased by 3 is greater than or equal to -26:

X×2=10
X=10÷2
X=5
Proof: 5×2=10
Speed = Distance/Time
So, speed
= 300 km/2h
= 150km/h
= (150 × 1000m) / 3600s
= 150000m/3600s
= 41.66m/s [approximately]