X² - 12x + 36 = 0 We know this is in standard form so we can use the quadratic formula. Indeed like a previous solution posted you can use factors, that is quicker but this will always work so let's see.
The answer is 2 in 20 or 1 in 10, all you have to do is add up the total number of marbles and then have the number of yellow in the total. So 2 in 20. Hope this helps you!
