You could say - "I paid a total of 7.000 dollars on food, while also spending over 8.000 on travel." You can't use the phrase "next year" with this sentence because in the first part of the sentence you are talking about the past, so the second part of the sentence also talks about the past too.

You would not say “while also spended” because SPENDED is past tense (talking about the past) and if you are going to travel the next year, it’s in the future or future tense, which would be SPENDING or GOING TO SPEND depending on context

No, the sentence is far from correct. There are 4-5 odd uses, such as the use of 3 decimal points with currency, the use of any decimal point with the word 'dollar'. Or should it be 7,000? Referring to 'spending' in a future tense doesn't make sense. Is the spending planned? Or should it not be future tense? It's not clear. BUT I'm sorry to say that your change makes it even worse. 'spended' is never correct. It is not a word.

Hello, Mona. I think this sentence is a little weird. As "I paid a total of 7,000 dollars for food" seems like the action having been taken already, while in the latter part of the sentence it mentions "next year". I wonder if you can give the context of this sentence. And the past tense of "spend" should be "spent". Thanks!

This is kinda weird for me too. I don't know whether you mean this or not : I paid a total 7.000 dollars "JUST" for food, while "I AM GOING TO SPEND" over 8.000 dollars on travel in the next year.