Since 16 - 29 are systems of equations, the easiest way would possibly be through elimination because all you'd have to do is add the two equations then solve for your variable then plug in that number to one of the equations and then solve for the remaining variable, and then you'd get an ordered pair as your solution.
Circumference of Circle=C, =2(pi)(radius)
Radius of Circle=r
Side of square=x
f(x)=area of circle
g(r)=area of square
16 feet=C+4x
C=16-4x
2(pi)(r)=16-4x
2(pi)(r)=2(8-2x)
(pi)(r)=8-2x
r=(8-2x)/(pi)
x=(8-(pi)r)/2
f(x)=(pi)(r^2)
f(x)=(pi)((8-2x)/(pi))^2
f(x)=((8-2x)^2)/(pi)
f(x)=((64-32x+4x^2))/(pi)
g(r)=((8-(pi)r)/2)^2
g(r)=((64-16(pi)r+(pi)^2(r^2))/4
OK so for the first one, you have 3 TVs for 1200 dollars. The 90 dollars is a 1 time cost. so what u want to do is multiply 3 by 1200 and then add 90.
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