Answer:
p=$300 and q=30 clock radio
Step-by-step explanation:
we have
p ----> is the price
q ----> is the quantity
[tex]p+3q=390[/tex] ----> equation A
[tex]p-7q=90[/tex] ----> equation B
Solve the system of equations by graphing
Remember that the solution is the intersection point both graphs
using a graphing tool
The intersection point is (300,30)
see the attached figure
therefore
The solution is
p=$300
q=30 clock radio