we have the equation
[tex]A=(\frac{q+k}{4})\cdot m[/tex]Solve for q
That means
Isolate the variable q
so
step 1
Multiply by 4 both sides
[tex]4A=(q+k)\cdot m[/tex]step 2
Divide both sides by m
[tex]\frac{4A}{m}=(q+k)[/tex]step 3
Subtract k both sides
[tex]q=\frac{4A}{m}-k[/tex]