The question is asking us to find the temperature which is 15 degrees lower than seven degrees Celsius.
The mathematical symbol used for lower than is a subtraction sign that is -.
15 lower than 7 degree = 7-15 = -8.
7 and 15 have opposite sign so will be subtracted .The answer will take the sign of the bigger number.
The temperature that is 15 degrees lower than seven degrees Celsius is -8°C
