What was john’s age 4 years ago, if he is y years old now?

To find his age 4 years ago, you need to subtract 4 from his current age.

His current age is Y, so his age 4 years ago is: y - 4

gdp is the best phrase!

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: