The expression for a linear equation in thee slope-intercept form is ,
y = mx + b
the slope = m= (y2-y1)/ (x2-x1)
y-intercept is (0, b)
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Rearreging tha expresion
y = 3x + 4
The rate is the slope (m) = 3
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Answer
the constant, in this case, is 3