Final answer:
When evaluating a − b with a being -2.5 and b being 2/5, the expression simplifies to -27/10 or -2.7.
Step-by-step explanation:
To evaluate a − b when a is equal to -2.5 and b is 2/5, we simply substitute the values into the expression. The calculation is as follows:
a − b = (-2.5) − (2/5)
Since we are dealing with a fraction for b, we need to express -2.5 with a common denominator to make the subtraction straightforward. -2.5 is the same as -5/2. To have a common denominator with 2/5, we can multiply both the numerator and denominator of -5/2 by 5 to get -25/10.
Now, with a common denominator, we can subtract:
(-25/10) − (2/10) = (-25 − 2) / 10 = -27/10
Therefore, the simplest form of a − b is -27/10 or -2.7.