Answer
15.20
Work Step by Step
As a negative number is being subtracted from a negative number, this problem is the same as adding the two numbers together, because a negative number subtracted from a negative number will result in a positive answer. We can therefore treat this problem as an addition problem.
First, write the numbers under one another by lining up the decimal places (see Table 1 below).
Next, add trailing zeros so the numbers have the same length (see Table 2) below.
Now, add down the columns (see Figure 3 below).