All isotopes of technetium are radioactive, but they have widely varying half-lives. if an 800.0 g sample of technetium-99 decays to 100.0 g of technetium-99 in 639 000 y. what is it's half-life?

What does x = in this equation x+3+2x=x+5

You have a square piece of cardboard that measures 14 inches on each side. to build a box, you cut congruent squares out of each corner of the cardboard. use the picture to find the area of the cardboard you were used to build the box

Aladder that is 20ft long is leaning against the side of a building. if the angle formed between the ladder and the ground is 75 degrees how far is the bottom of the from the base of the building?