Hi there,

The problem says that 4/5 of ttl nbr of shirts were sold. And the question is : what is the fraction already sold? Possible choices 2/10; 3/10; 8/10; 6/12

This is a tricky question : actually they ask you the fraction already sold when they already give you that 4/5 of ttl nbr of shirts were sold which is the same thing. So, 4/5 is the answer. The thing is 4/5 does not appear in the choices...

Equivalent (equal) fractions :it is easy to imagine a fraction of 1/2. For example : eating 4 apples out of 8 is eating the half (4/8). Getting 10 out of 20 on a test is half of the points (10/20). So we have many fractions like 4/8, 10/20 that are actually the same fraction 1/2. You can see that if you devide the numerator and the denominator of 4/8 by 4 you'll get 1/2 and if you devide the numerator and the denominator of 10/20 by 10 you'll also get 1/2.

There is a trick to know if two fraction are equivalent (equal). For example, take 4/8 and 10/20. Multiply the numerator of the first with the denominator of the second : 4*20=80 and multiply the numerator of the second with the denominator of the first : 10*8=80. Same thing ! so the 2 fractions are the same !!!

Now, you have 4/5 and you want an equivalent fraction from the choices : 2/10; 3/10; 8/10; 6/12

The answer is 8/10 because :

1) if you devide the numerator and the denominator of 8/10 bu 2 you'll get 4/5 so that means they are equal

or

2) use the other trick : compare 4/5 with 8/10 by multipling the numerator of the first with the denominator of the second : 4*10=40 and multipling the numerator of the second with the denominator of the first : 8*5=40. They are equal so the fraction is the same.

I hope it helps you