Ann bought 5/8 kg of tomatoes to make a salad dish .2/5 of the tomatoes were rotten and the rest were fresh .what was the mass of fresh tomatoes ?

So 3/5 of them were fresh

3/5 * 5/8 = ?

Your questions are almost identical. Look them over carefully
If you take out x/m of something
them 1- x/m = (m-x)/m is left
like
take out 99/100
then
1/100 is left
(100-99)/100 = 1/100

To find the mass of the fresh tomatoes, we need to subtract the mass of the rotten tomatoes from the total mass of the tomatoes that Ann bought.

First, let's calculate the mass of the rotten tomatoes:
The question states that 2/5 of the tomatoes were rotten. So, we need to find 2/5 of 5/8 kg.

To do this, multiply these fractions:
2/5 * 5/8 = (2 * 5) / (5 * 8) = 10/40 = 1/4

Therefore, the mass of the rotten tomatoes is 1/4 kg.

Now, we can find the mass of the fresh tomatoes:
To do this, we subtract the mass of the rotten tomatoes from the total mass that Ann bought.

Total mass - Mass of rotten tomatoes = Mass of fresh tomatoes
5/8 kg - 1/4 kg = ?

To make the fractions have the same denominator, we need to find the least common multiple (LCM) of 8 and 4, which is 8. Here's the calculation:

(5/8 * 8/8) - (1/4 * 2/2) = 40/64 - 2/8 = (40 - 16) / 64 = 24/64

Simplifying the fraction by dividing both the numerator and denominator by their greatest common divisor (which is 8) gives us:

24/64 = (24/8) / (64/8) = 3/8

Therefore, the mass of the fresh tomatoes is 3/8 kg.