-2.1b +5.3= b -- 3.1b + 5.3

does is have one solution or infinitely many solutions ? Why ?

infinitely many solutions.

Step-by-step explanation:

Ok, our equation is:

-2.1*b + 5.3 = b - 3.1*b + 5.3

now, simplifyng the right side, we have:

b - 3.1*b + 5.3 = (1 - 3.1)*b + 5.3 = -2.1*b + 5.3

Then our initial expression is:

-2.1*b + 5.3 = -2.1*b + 5.3

So in both sides of the equality we have the exact same thing, so this is a trivial equality.

This means that the equality will remain true for any value of b, which means that we have infinitely many solutions.

correct answer:

b.(19,-2)