The half-life of a radioactive kind of manganese is 21 minutes. If you start with 2,560 grams of it, how much will be left after 84 minutes?​

Arley is building a model of a city map. in one part of the city, three roads form a right triangle, which harley draws as triangle abc, with the following measures: m∠b=90° and m∠a=30°. in his scale model, the hypotenuse of triangle abc, ac¯¯¯¯¯¯¯¯, has a length of 817−−√ cm. what is the value of a (the length of bc¯¯¯¯¯¯¯¯)?

Determine the number of girls in a math class with 87 boys if there are 25 girls for every 75 boys

You spin the spinner shown below once. each sector shown has an equal area. what is p(beaver ) p(beaver)? if necessary, round your answer to 2 2 decimal places.