−25+4/9b= −21

To solve for b, first we need to get rid of the constant term (−25) on the left side of the equation.

−25 + 4/9b = −21

Add 25 to both sides:

4/9b = 4

Now we can isolate b by multiplying both sides by the reciprocal of 4/9:

b = 9/4 * 4

b = 9

Therefore, the solution to the equation is b = 9.