
Hope you could get an idea from here.
Doubt clarification - use comment section.
We have a system of equations in two variables, namely, a and c. Use the substitution to find a and c.
Given that
, we have
, so that

Take the derivative and find the critical points of
:

Take the second derivative and evaluate it at the critical point:

Since
is positive for all
, the critical point is a minimum.
At the critical point, we get the minimum value
.
Answer$10 65 cents
Step-by-step explanation:
20/4= $5 40/10= $4 .05 x 30= $1.50 and add those together to get $10.50 then add the 15 pennies which is $10.65
There is one solution: w=3