16Hit1600
AlgebraHardSlope of a line built from two other lines' intercepts

Algebra practice question

In the xy-plane, line m has the same y-intercept as the line 5x + 2y = 20 and the same x-intercept as the line x + y = 8. What is the slope of line m?

Answer: -5/4 or -1.25

The y-intercept of 5x + 2y = 20 is 10 and the x-intercept of x + y = 8 is 8, so m passes through (0, 10) and (8, 0): slope = −10/8 = −5/4.

Common wrong answers

If you answered 5/4
5/4 loses the sign.
If you answered -4/5
−4/5 inverts the ratio.
If you answered -5/2
−5/2 is the slope of the first line.

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