5. Samantha has 30 coins, consisting of 20c and 50c, which total $13.50. How many of each does she have?​

50c = 25

20c = 5

Step-by-step explanation:

50x + 20y = 1350 (1) - multiply y by one.

x + y = 30 (2) - multiply y by  20.

50x + 20y = 1350 (1)

20x + 20y = 600 (2)

If you treat it like simultaneous equations, you take away equation 2 from equation 1.

30x = 750

x = 25

Then, once you have your value of x, you can substitute it back into the original equations to find your answer.

x + y = 30

25 + y = 30

y = 5

Then you have your answer. Hope this helps :)

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: