The answer to the equation is r=-9.8
First combine the like terms of the equation.
7.4-9-2r=18
7.4+(-9)=-1.6
-1.6-2r=18
Continue by adding 1.6 to both sides of the equation to isolate the variable.
-1.6-2r=18
+1.6 +1.6
-----------------
-2r=19.6
Divide -2 on both sides.
=

r=-9.8