Earth's energy budget
Earth stays in balance by radiating away as much energy as it absorbs; albedo and greenhouse gases set that balance.
A worked example
A surface with an albedo of 0.80 reflects 80% of the sunlight landing on it, so of 1 000 W per square metre arriving, only 200 W is absorbed.
The mistake people actually make
Greenhouse gases do not block incoming sunlight; they absorb the longer-wavelength infrared that Earth radiates back out. Percentages in an energy budget are all shares of the same arriving total, so they are subtracted from 100, not from each other.