Read the excerpts from Team Moon and the NASA article. Thirty seconds! Now would not be the time for the two Bobs to miscalculate, miscount, or lose their superhuman powers of concentration. They could not afford to be wrong.

When the lunar module lands at 4:18 p. m. EDT, only 30 seconds of fuel remain. Armstrong radios "Houston, Tranquility Base here. The Eagle has landed."

A reader can best combine the information in the excerpts to

understand that managing the moon landing while the lunar module had 30 seconds left of fuel required intense concentration.
understand that having only 30 seconds of fuel could easily have become a disaster while Armstrong was landing the lunar module.
understand that Armstrong radioed mission control when the lunar module landed on the moon at 4:18 p. m. EDT.
understand that it was impossible for the lunar module to land on the moon with only 30 seconds left of fuel.