Pressure Sensor KP125, input Pressure to O/P voltage conversion,
The datasheet shows the calibration curve in fig.3.  By eyeball, you can see that 80 kPa would correspond to ≈2.6 V

Notice that the calibration curve is linear.  As you've noticed already, the datasheet gives you two points on the curve.  That allows you to calculate the slope of 0.053 V/kPa.