Answer:
193.586 deaths per 100,000
Step-by-step explanation:
The cause-specific mortality rate for a disease in a per 100,000 basis is determined as the total number of deaths due to the disease multiplied by 100,000 and divided by the average (mid-year) total population.
There were 597,689 deaths due to diseases of the heart in a population of 308,745,538 people. The cause-specific mortality rate for diseases of the heart per 100,000 in this population is:

The mortality rate is 193.586 deaths per 100,000.
Combine like terms then you have your answers
Remark
The proof is only true if m and n are equal. Make it more general.
m = 2k
n = 2v
m + n = 2k + 2v = 2(k + v).
k and v can be equal but many times they are not. From that simple equation you cannot do anything for sure but divide by 2.
There are 4 combinations
m is divisible by 4 and n is not. The result will not be divisible by 4.
m is not divisible by 4 but n is. The result will not be divisible by 4.
But are divisible by 4 then the sum will be as well. Here's the really odd result
If both are even and not divisible by 4 then their sum is divisible by 4
Answer: r= -3
Next 3 terms following 54 are -162, 486, -1458
Step-by-step explanation: