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,
![x+y+z=9](https://img.qammunity.org/2020/formulas/mathematics/middle-school/zac2pjvpmyhy5ikcuz0epyem579lwvg3a5.png)
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,
![3x+2y+z=18](https://img.qammunity.org/2020/formulas/mathematics/middle-school/zu8i1gusprg9g0liyvydspcqjwjih4povc.png)
Also, widget B is one more than the sum of widgets A and C. So,
![y=x+z+1](https://img.qammunity.org/2020/formulas/mathematics/high-school/g7hzqew060f34gbjs07jupfdn5zi9bf9x3.png)
Now, we have 3 equations and 3 unknowns.
![x+y+z=9](https://img.qammunity.org/2020/formulas/mathematics/middle-school/zac2pjvpmyhy5ikcuz0epyem579lwvg3a5.png)
![3x+2y+z=18](https://img.qammunity.org/2020/formulas/mathematics/middle-school/zu8i1gusprg9g0liyvydspcqjwjih4povc.png)
⇒
![x+z=y-1](https://img.qammunity.org/2020/formulas/mathematics/high-school/x46rxh029ergjnrtdv3736mvyya1hecepx.png)
Now, using the first and third equation, we get
![y+y-1=9\\2y=10\\y=5](https://img.qammunity.org/2020/formulas/mathematics/high-school/xceu9jvfvc0h8sakcjp0sd23dq10z4i3r0.png)
Plug in 5 for
in the first 2 equations. This gives,
⇒
![x+z=4](https://img.qammunity.org/2020/formulas/mathematics/high-school/3ho7t2jdsploslklxhgxiq7xc1w2nne8or.png)
⇒
![3x+z=8](https://img.qammunity.org/2020/formulas/mathematics/high-school/kalpzcyhgodroqdt0s5quglh28kg6m9mwj.png)
Subtracting the above 2 equations, we get,
![x-3x+z-z=4-8\\-2x=-4\\x=2](https://img.qammunity.org/2020/formulas/mathematics/high-school/zpnwzcn6rbx0ezv2lir7nwn5biet0mur9k.png)
Using the value of x in the above equation, we find z.
![x+z=4\\2+z=4\\z=2](https://img.qammunity.org/2020/formulas/mathematics/high-school/a553usy5fh9b3f1icavjt5oslklcv1uxpx.png)
Therefore,
![x=2,y=5,z=2](https://img.qammunity.org/2020/formulas/mathematics/high-school/bfhhtevtke45dz30n4gxtuvi43i1w4lnvl.png)
Hence, number of widgets A and C are 2 each, widgets B are 5.