Apply the distributive property:
-20x-30<-18+6+4x
Addition property of equations and inequalities––add 20x to both sides:
-30<-12+24x and add 12 to both sides: -18<24x.
Division (by a positive number) property of equations and inequalities––divide by 6:
-3<4x; divide through by 4: -3/4<x, so x>-3/4 is the solution.
TEST
Put x=0. This should satisfy the original inequality:
-5(6)<-12, that is -30<-12 which is true.
Put x=-1/4 which should also satisfy the inequality:
-5(5)<-13, that is -25<-13
Put x=-1 which shouldn't satisfy the inequality:
-5(2)<-12-4 gives -10<-16 which is not true.
Put x=-3/4 which shouldn't satisfy the inequality:
-5(3)<-15, that is -15<-15 which is not true.