A rectangular solar panel is 20 cm by 30 cm. By adding the same amount to each dimension, the area is doubled. How much is added? The voltage V across a certain electronic device is related to the...

A rectangular solar panel is 20 cm by 30 cm. By adding the same amount to each dimension, the area is doubled. How much is added?

The voltage V across a certain electronic device is related to the temperature T (in °C) by V = 4.00T
 0.200T². For what temperature(s) is V = 15.0 V?