# Tag Info

Since this is linear interpolation it boils down to solving a linear equation $y = a + b t$ You can substitute the following $y = y_s$, $a = y_1$(intercept) and $b = y_2 - y_1$ (slope) to get the following $$y_s = y_1 + t(y_2 - y_1)$$ $$y_s - y_1 = t(y_2 - y_1)$$ $$\frac{y_s - y_1}{y_2 - y_1} = t$$ The same thing happens for points where you can write D = ...