I’m carbon cycle, co2 is mainly stored in

rocks

Explanation:Google

Most of Earth's carbon—about 65,500 billion metric tons—is stored in rocks. The rest is in the ocean, atmosphere, plants, soil, and fossil fuels. Carbon flows between each reservoir in an exchange called the carbon cycle, which has slow and fast components.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

because if the tool that you are using is not balanced it there would be false mass.