To determine which pairs of points lie on the given linear function \( C = 1.25m + 25 \), we can plug in the values of \( m \) (miles driven) from each point into the equation and check if we get the corresponding value of \( C \) (total cost).
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For point (30, 4):
- Here, \( m = 4 \).
- Calculating \( C \): \[ C = 1.25(4) + 25 = 5 + 25 = 30 \] So point (30, 4) is valid.
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For point (35, 8):
- Here, \( m = 8 \).
- Calculating \( C \): \[ C = 1.25(8) + 25 = 10 + 25 = 35 \] So point (35, 8) is valid.
Now let's check the other pairs:
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For point (4, 30):
- Here, \( m = 30 \).
- Calculating \( C \): \[ C = 1.25(30) + 25 = 37.5 + 25 = 62.5 \] So point (4, 30) is not valid.
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For point (8, 35):
- Here, \( m = 35 \).
- Calculating \( C \): \[ C = 1.25(35) + 25 = 43.75 + 25 = 68.75 \] So point (8, 35) is not valid.
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For point (2, 22.5):
- Here, \( m = 2 \).
- Calculating \( C \): \[ C = 1.25(2) + 25 = 2.5 + 25 = 27.5 \] So point (2, 22.5) is not valid.
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For point (4, 20):
- Here, \( m = 4 \).
- Calculating \( C \): \[ C = 1.25(4) + 25 = 5 + 25 = 30 \] So point (4, 20) is not valid.
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For point (2, 2.5):
- Here, \( m = 2.5 \).
- Calculating \( C \): \[ C = 1.25(2) + 25 = 2.5 + 25 = 27.5 \] So point (2, 2.5) is not valid.
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For point (4, 5):
- Here, \( m = 4 \).
- Calculating \( C \): \[ C = 1.25(4) + 25 = 5 + 25 = 30 \] So point (4, 5) is not valid.
Only the first set of points—(30, 4) and (35, 8)—are valid according to the linear function \( C = 1.25m + 25 \).
Therefore, the answer is: (30, 4) and (35, 8).