Half-life of Po-210 is 140 days. If the initial mass of the sample is 5 kg, how much will remain after 420 days.

]supplementary angles are two angles that add up to . • complementary angles are two angles that add up to degrees. • adjacent angles share a and a • congruent angles have the measure. • an triangle has one angle that is greater than 90 degrees. • a triangle with angles 45°, 45°, and 90° would be a triangle