The answer is c because all you are doing here is subbing the variable r for 5b.
Answer:
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For this problem you have to isolate the variable. To do this you must inverse the operations. Multiply 18 by 5, then divide by 12 to get your answer of 7.5
(-4) is the same as x, so looking the conditions that are the results for the function, you realize:
-2 is the result of the function to the values of X that are under -3: the result will be -2 if x < -3
x < -3 ; x = -4 ; -4 < -3 (it's true), in other words, -4 is less than -3, so f(-4) = -2