P6 Math: Red and White Roses Ratio

There are 60 roses in a box. 30% of the roses are red roses while the rest are white roses. How many of red roses must be added so that the number of red roses will become 40%?

At first:       Red : White : Total = 30 : 70 : 100 or 3 : 7 : 10

At the end: Red : White : Total = 40 : 60 : 100 or 2 : 3 : 5

In this problem, we have to remember that the number of White is unchanged.

So, we transform both ratio to have equality for the White part

3 : 7 : 10 --> 9u : 21u : 30u

2 : 3 : 5   -->14u : 21u : 35u

At first, there is 60 roses --> 60 = 30u, u = 2

Additional red roses is 14u - 9u = 5u --> 10 red roses.