Let n = total number of babies born
Let n₁ = 34 be the number of boy babies born.
Let n₂ = number of girl babies born.
Therefore
n₁ + n₂ = n
34 + n₂ = n
n₂ = n - 34 is the numbe of girl babies born.
Because the 54% of babies born in the week were boys, therefore
34/n = 54%
or
34/n = 0.54
Multiply each side by n.
34 = 0.54n.
n = 34/0.54 = 62.96
We can only have countable number of babies, therefore
n = 63.
n₂ = n - 34
= 63 - 34
= 29
Answer: 29 girl babies were born in the week.