Answer:
The rate of flow is 75.4 kg/s.
Explanation:
Given that,
Diameter of pipe = 18.0 cm
Diameter = 9.00 cm
Pressure 
Pressure in the smaller pipe 
We need to calculate the velocity of longer pipe
Using formula of velocity


Put the value into the formula


....(I)
We need to calculate the velocity of smaller pipe
Using Bernoulli's equation


Put the value into the formula





Put the value of v₂ in the equation (I)


We need to calculate the flow
Using formula of flow rate

Where, Q = flow rate
A = area
v = velocity
Put the value into the formula


We need to calculate the rate of flow
Using formula of rate

Put the value into the formula


Hence, The rate of flow is 75.4 kg/s.