Question

One half of the birds at the pet store are yellow . Tara buys one of the yellow birds. Then one third of the birds at the store are yellow. How many yellow birds were at the pet store before Tara bought one ?

Answer 1

If there were x birds, then

x/2 - 1 = 1/3 (x-1)
x = 4

So, there were originally 4 birds and 2 yellows.

After the sale, there was 1 yellow of 3 birds left.

So, answer the question.

Or, to eliminate one step, consider making x the number of yellow birds.

x - 1 = 1/3 (2x-1)
x = 2