A scientist models the number of grams of a radioactive substance with the expression 15•(1/2)^d/5, where d is the number of days since the sample was measured.
Math
1. After how many days has half of the substance disappeared through radioactive decay?

Micah solves a linear equation and concludes that x = 0 is the solution. his work is shown below. (1 – 3x) = 4(– + 2) 0 = x which statement is true about micah’s solution?

The figure shows triangle def and line segment bc, which is parallel to ef: triangle def has a point b on side de and point c on side df. the line bc is parallel to the line ef. part a: is triangle def similar to triangle dbc? explain using what you know about triangle similarity. part b: which line segment on triangle dbc corresponds to line segment ef? explain your answer. part c: which angle on triangle dbc corresponds to angle f? explain your answer. asap

Awindow washer cleans 42 windows in 2 hours. at this rate, how many windows did he clean in 180 minutes.