Ok so first lets make the equation
3x=5+2x
we subtract 2 on each side
x=5
5*(n-20)= (4n+4) / 2 is the equation, please say what you need answered.
You take the total number of picture and multiply it by .12, which will get you the total number of black and white photos only.
600(.12)= 72
He would need 2.8 bouquet's to make 20 dollars because i had to round
i hope this helped