On a particular thermometer the 0°C mark and the 100°C mark are 25 cm apart. The mercury level is at a point 15 cm up the scale. Find the temperature indicated by the thermometer.

L = 25 * T / 100     would describe this thermometer where L is the distance from the bottom of the scale

T = 100 L / 25 = 4 L       rewriting the above equation

T = 4 ^ 15 = 60 deg C

the current is 0.6

voltage ÷ resistance = current

so 12 ÷ 20 = 0.6