Final answer:
Approximately 2.60 billion tons of carbon came from the creation of concrete and steel.
Step-by-step explanation:
To determine how much carbon came from the creation of concrete and steel, we need to calculate 7% of the world's total carbon emissions in 2018. The total carbon emissions in 2018 was 37.1 billion tons, so we can calculate:
7% of 37.1 billion tons = (7/100) x 37.1 billion tons = 2.597 billion tons.
Therefore, approximately 2.60 billion tons of carbon came from the creation of these building materials.