With everything else as constant (the planet's gravity, itself), then yes, this is true. But, if the planet's gravity still exists, then the Sun's gravitational force doesn't matter as much because of the astronomical distance between the two bodies.
The correct answers are:
- barter;
- gold;
The barter and the gold were the most common things used in the Ancient world for trade. The barter, or bartering, is essentially the exchange of goods, or rather one good for another good. That of course goes in accordance to the valuation of the goods, so for example, one goat would be traded for ten rabbits. The gold, on the other hand, was a materialistic thing used for exchange of goods. The gold was very highly valued, so each amount of gold had certain valuation, and according to its valuation the people were able to purchase certain goods with it. The gold was in a many ways what the paper money are in the present day.
Because as you approach the center it gets warmer
I wish I could help:(.......
There are five contour lines between 180 and 80 so...

2. 20m is the answer