To determine the number of days that an employee work in a week, we simply use dimensional analysis and multiplying the number of works per week with the number of weeks in total for a year. That is,
employee works = (5 days per week)(49 weeks per year)
=245 days
Since we know that a number is divisible by 3 if the sum of all digits is divisible by 3.
Let us check which digits will make 371? divisible by 3.

11 is not divisible by 3.
Now let us check other digits as well.
12 is divisible by 3.

15 is also divisible by 3.

18 is divisible by 3 as well.
Therefore, 1, 4 and 7 in tenth place will make our number divisible by 3 and our numbers will be 3711, 3714 and 3717.
Y = -7x + 2
y = 9x - 14
-7x + 2 = 9x - 14
14 + 2 = 9x + 7x
16 = 16x
1 = x
y = -7x + 2
y = -7(1) + 2
y = -7 + 2
y = -5
solution is : (1,-5) <==