Set up as fractions and use cross multiplilcation to solve for the unknown.
These are our fractions from the information we are given; the winners represent the numerators (and x is the unknown, becuase we don't yet know how many winners there will be with 50000 participants). Note that the denominator on the first fraction is (1476 + 5) because we want it to represent TOTAL amount of particpants in the ratio:
Now cross multiply by multiplying numerators and denominators that are ACROSS from each other, so 5 * 50000 and 1481 * <em>x; </em>now we have:
250000 = 1481x
Now to isolate x (to know its value) we need to divide both sides by 1481, and we are left with:
First, you find the brother's age by dividing mary's age by 4. 16 ÷ 4 = 4 Now that you have two ages, you can just make a list to find the answer. 16 and 4 18 and 6 20 and 8 22 and 10 24 and 12