The answer is supposed to be 10.5 because
When 2 red is used then 7 white do
If 3 is used then
Red 2 3
White. 7. 10.5
Ok so working here
Since we know when 2 red is used we use 7 white then how much red left? 3-2= 1 red left so one red will equal to how much white?
So then one red has to equal to 3.5 white since u dividing to find into half since it is only two red
U gotta follow on a price of paper then u will only understand