The weight is 45 N, because the three chains hold the sign, and each contributes 15 N.
Notice that the mass would be the weight/acceleration of gravity, m = 45/9.8 kg. But they ask the weight (force, so Newtons)
<span>division of Earth's history into time units based largely on the types of life-forms that lived only during certain periods.</span>
I think your in the wrong section kid. This should be in Earth and Space Science.
Все написано в скобках правильно
The atomic number of an element is the number of protons the element has, so the element with the atomic number 55 has 55 protons.