Which equation indicates a positive slope in a linear relationship between x and y?

• A. y = −Rx + 18
• B. y = Rx − 18
• C. y = −Rx − 18
• D. y = Rx + 18

Answer: (D)

In a linear equation written as y = mx + b, the slope is the coefficient m in front of x. A positive slope means the line rises as x increases, so the x-term must have a positive coefficient.

Here, the coefficient of x is either −R or +R. If R is positive, the equations with +R x have positive slope, while the ones with −R x have negative slope. Among the options with a positive slope, the one that also has a positive y-intercept (the constant term +18) clearly shows a line that starts above the origin and increases as x grows. That combination makes the positive slope most evident.

So the equation with Rx + 18 best demonstrates a line that rises as x increases. The other positive-slope option would still rise, but its intercept is negative, which makes the upward trend less immediately apparent in graphical intuition.