Question

4.7+x=3.1
Solve for
x
.
x=

Answer 1

4.7 + x = 3.1

Subtract 4.7 from both sides to isolate x

x = 3.1 - 4.7 = -1.6

Answer 2

X=  -1.5 

4.7 + X = 3.1 
move the x and it becomes 
4.7 = 3.1- X 
then divide 4.7 by 3.1. then you get 1.5 but you cannot have a negative variable so you make the 1.5 negative !