A thermocouple with the test junction at t °C on the gas thermometer scale and the reference junction at the ice point gives the electromotive force (e.m.f.) as: e = 0.2t - 5 × 10⁻⁴ t² mV. The millivoltmeter is calibrated at ice and steam points. What will be the reading on this thermometer when the gas thermometer reads 70°C?