Which equations have one solution and which have infinitely many solutions?

Step-by-step explanation:

1).

 Since left side of the given equation is not equal to the right side, there will be one solution to the given equation.

2). -2.1b + 5.3 = b - 3.1b + 5.3

   -2.1b + 5.3 = -2.1b + 5.3

Since left side of the equation is exactly same as right side of the equation.

Equation will have infinitely many solutions.

3).

Since left side of the given equation is not equal to the right side, there will be one solution to the given equation.

4). 5.7c - 1.5 + 3.2c = 7.8c - 1.5 + 1.1c

   8.9c - 1.5 = 8.9c - 1.5

 Left side of the equation is same as right side of the equation.

Therefore, there will be infinitely many solutions of the equation.

27

step-by-step explanation:

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0