Red apples at the end: 2 units
Green apples at the end: 1 unit

She sold half of her red apples away correct? This means that she had half of her red apples left.

She must have started out with 4 units of red apples, with 2 units being sold. And realise that the sold 35 fewer green apples than red apples.

Red apples sold: 2 units
Green apples sold: 2 units - 35

So,
total red apples at first: 4 units
total green apples at first: 3 units - 35

And therefore,
total apples at first: 7 units - 35

7 units - 35 = 455
7 units = 490
1 unit = 70

Great! We found the value for 1 unit. All we need to do is to find 4 units.

4 units = 280

So she had 280 red apples at first.

Sorry ,I don’t understand how do I know at the beginning my green apple has 2 units then changed to 1 unit ? Thanks

In the end, red apple is twice green apple.

A good indication that red apples left = 2 units and green apples left = 1 unit.

Red apples become 2 units in the end because half the original red apples have been sold.

This is a strong indication that red apples sold = 2 units.

35 fewer green apples are sold as compared to red apples, so green apples sold = 2 units - 35.

In no part of the question is the green apples at the beginning 2 units. You probably misunderstood the question if you obtained that.

It’s a good idea to start from the end in this case.

Sorry what I meant is , how do u know that the green apple sold were 2 unit?

Remember we obtained red apples sold = 2 units?

35 fewer green apples are sold (than red apples).

We are not sure of how many green apples are sold, but in terms of units, we can say that green apples sold = 2 units - 35.

I repeat. Green apples = 2 units minus 35. I emphasise on the word minus. I never said that green apples = 2 units.

The other responder has labelled the model for it where the missing “35 apples” forms part of the model.

Thank you , I understand now