Answer:
Number of widgets A and C are 2 each, widgets B are 5.
Step-by-step explanation:
Let
be the number of widgets A,
be the number of widgets B and
be the number of widgets C.
As per the question,
On a given day, total 9 widgets are produced. So,

Cost for 1 widget A is $3. So, cost of
widgets A is 3x.
Cost for 1 widget B is $2. So, cost of
widgets A is 2y.
Cost for 1 widget C is $1. So, cost of
widgets A is z.
Now, total cost of the widgets is $18. So,

Also, widget B is one more than the sum of widgets A and C. So,

Now, we have 3 equations and 3 unknowns.


⇒

Now, using the first and third equation, we get

Plug in 5 for
in the first 2 equations. This gives,
⇒

⇒

Subtracting the above 2 equations, we get,

Using the value of x in the above equation, we find z.

Therefore,

Hence, number of widgets A and C are 2 each, widgets B are 5.