Let the number of months it will take be n.
From the question, 2 assistant caregivers are hired every month.
So the total number of assistant caregivers in n months is 1 + 2n
From the question, 1 senior caregiver is hired every month.
So the total number of senior caregivers in n months is 12 + n
Since n is the number of months when the number of assistant caregivers equals the number of senior caregivers
Then
12 + n = 1 + 2n
12 - 1 = 2n -n
Which implies that n = 11.
12 + n = 12 + 11 = 23
Hence, there are 23 of each type and it will take 11 months