16Hit1600
AlgebraHardShifting a line to pass through a point

Algebra practice question

In the xy-plane, line ℓ has the equation 4x + 5y = 12. Line m is parallel to ℓ and passes through the point (2, 4). Line m has the equation 4x + 5y = c, where c is a constant. What is the value of c?

Answer: 28

Parallel lines share the left side; substituting (2, 4) gives 8 + 20 = 28.

Common wrong answers

If you answered 12
12 is the constant of line ℓ.
If you answered 16
16 adds 8 and 8, using 4 for both coefficients.
If you answered -28
−28 has the sign wrong.

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