Question

b+9
_____ =-3 what is b? step-by-step.

12

Answer 1

we have:
\[\frac{ b+9 }{ 12 }=-3\]
Now, algebraically that means a "proportion", so we'll cross-multiply:
\[b+9=-3(12)\]
The -3 has an invisible "1" below it, so multiplying a number by one gives me the same number.
Let's operate that multiplication:
\[b+9=-36\]
Now, let's substract 9 to each side to get:
\[b+9-9=-36-9\]
the 9s will simply so we'll end up with:
\[b=-36-9\]
We know that if we substract a number from a negative number, is the same as summing the numbers in a negative form:
\[b=-45\]
And we've found the value of b.