X+y+z=1
X-2y+3z=2
X+z-5=0

x+y+z=1

x=1/(y+z)

1/(y+z)-2y+3z=2  

1-2y²-2yz+3yz+3z²=2(y+z)

(1-2y²+yz+3z²)/2=y+z

z=(1-2y²+yz+3z²)/2 -y/1

z=(1-2y²+yz+3z²-2y)/2

first, we define the variables:

x: number of years after 1950

f (x): amount of vinyl sold.

then, with the variables defined, we have:

68594 vinyl records were sold in 1958 > f (8) = 68594

91299 vinyl records were sold in 1961 > f (11) = 91299

38720 vinyl records were sold in 1952 > f (2) = 38720

161743 vinyl records were sold in 1967 > f (17) = 161743

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step-by-step explanation: