David Gwyn J. answered 11/25/20
Highly Experienced Tutor (Oxbridge graduate and former tech CEO)
We need a bit of algebra with C = Cost and S = Songs
In general, C = sign-up + persong.S which is the slope intercept form of a straight line with Cost as the y axis, and Songs as the x axis. Sign up is the y intercept. And persong charge is the gradient of the line. So, if you want, we can easily plot the equations on Desmos Graphing or similar. You can then solve graphically by finding the point of intersection on the graph.
1st Choice equation is C = 5 + 1S (or C = 5 + S)
And Superstar equation is C = 0 + 3.5S (or C = 3.5S)
Solution is when they have same cost, so 5 + 1S = 3.5S
=> 2.5S = 5
=> S = 2
Hence they are equal at 2 songs.
Double-check by putting these numbers in the equations: 5 + 1(2) = 7 and 3.5(2) = 7 also. Hence the interesection point is (2, 7).
Jules J.
Thank you11/25/20