Answer
$-1.5$
Work Step by Step
The addends (numbers being added have) different signs.
To add two numbers with different signs, perform the following steps:
(1) Subtract the smaller absolute from the bigger absolute value.
$|-3.6|-|2.1|=3.6-2.1=1.5$
(2) Use the sign of the number with the bigger absolute value.
$-3.6+2.1=-1.5$
Thus, the sum is $-1.5$.
