To evaluate the expression, we'll follow the order of operations (PEMDAS/BODMAS).
First, let's simplify what's inside the parentheses:
3.15 - (21/20) = 3.15 - 1.05 = 2.1
Now, let's continue evaluating the expression:
-5(2.1) + 7
Next, perform the multiplication:
-5 * 2.1 = -10.5
Finally, complete the addition:
-10.5 + 7 = -3.5
Therefore, the value of the given expression is -3.5.