Answer:
the answer is -0.5.
Step-by-step explanation: First subtract 17 from 15 to know what u need to get. Know that u get -2, we have to figure out what to do to get -2 out of 4. First to get positive 2, multiply by 0.5, than since we need to get negative 2, add a negative in front. Hence, the answer is -0.5 .