Answer:
The prevalence of serious defects in this population at the time of birth is 10%.
Step-by-step explanation:
The prevalence of serious defects is the number of infants that were born with seriours birth defects divided by the total number of infants born.
In this problem, we have that:
There were 1000 newborn infants.
100 infants were born with serious birth defects.
Calculate the prevalence of serious defects in this population at the time of birth.
This is:

The prevalence of serious defects in this population at the time of birth is 10%.
Answer:
(8 * x) + 2x = 60
8x + 2x = 60
10x = 60
/10 /10
x = 6
8 is a constant that is being multiplied by an unknown number which we will name x. It is then being added to two times the unknown number(x), so we multiply x by 2, which is 2x. The final product will be 60, so in the equation it'll then equal 60.
We consider "a number" to be a variable that withholds an unknown value, which is x (or any other variable you prefer).
Answer: 7
Step-by-step explanation: I had this question before