It wasThey were too heavy and it was difficult to carry them. I was so tired. They were too heavy and it was difficult to carry them. I was so tired.

It wasThere were too heavy to carry them., so I was so tired. There were too heavy to carry, so I was so tired.

It wasThey were too heavy to carry them. I was so tired. They were too heavy to carry. I was so tired.

It wasThey were too heavy to carry them. I was so tired. They were too heavy to carry. I was so tired.

It wasThey were too heavy to carry them. I was so tired. They were too heavy to carry . I was so tired.

It wasThey were too heavy to carry them. I was so tired. They were too heavy to carry. I was so tired.

heavy would be a property of the textbooks, so you need to make the textbooks the subject of the sentence. "It" here reads as your experience of carrying them, but then heavy is not an adjective we would apply to that kind of experience. If you want to talk about your perspective of carrying them, you could say something like "It was too difficult to carry them, as they were too heavy"

I take bus wasTaking the bus would be easeier but I had no money s. So I broughtcarried the heavy textbooks on mby foot for twenty minutes. Taking the bus would be easier but I had no money. So I carried the heavy textbooks by foot for twenty minutes.

I take bus was easet would have been easier to take the bus but I had no money so I broughtcarried heavy textbooks on my foot for twenty minutes. It would have been easier to take the bus but I had no money so I carried heavy textbooks on foot for twenty minutes.

I take bus wasTaking the bus would have been easey, but I had no money s. So I broughtcarried my heavy textbooks on my foot for twenty minutes. Taking the bus would have been easy, but I had no money. So I carried my heavy textbooks on foot for twenty minutes.

I take bus wasTaking the bus would have been easeier but I had no money so I broughtcarried the heavy textbooks on my foot for twenty minutes. Taking the bus would have been easier but I had no money so I carried the heavy textbooks on foot for twenty minutes.

You included 思った which translates to “I thought”. Maybe “ I thought that taking the bus would be easier”

I take bus washought taking the bus would be easey but I had no money so I broughthad to go on foot carrying my heavy textbooks on my foot for twenty minutes. I thought taking the bus would be easy but I had no money so I had to go on foot carrying my heavy textbooks for twenty minutes.

I take bus wasf I took the bus, it would have been easey but I had no money so I broughtcarried the heavy textbooks on my foot for twenty minutes. If I took the bus, it would have been easy but I had no money so I carried the heavy textbooks on foot for twenty minutes.

"on foot" = "by walking" "on my foot" = the books were literally placed on your foot (which is a bit silly sounding)