21/3 -4 4/5 i do not get the question can you me because i did not understand

Element x decays radioactively with a half life of 8 minutes. if there are 450 grams of element x, how long, to the nearest tenth of a minute, would it take the element to decay to 37 grams?

What is the ratio for the surface areas of rectangle prisims shown below given that they are similar and that the ratio of their edge lengths is 7: 3

The sum of two numbers is 58. the first number is 8 less than half the second number. let  c  represent the first number. let  drepresent the second number. which statements about solving for the two numbers are true? check all that apply.the equation    represents the sum of the two numbers.the equation    represents the sentence “the first number is 8 less than half the second number.”the equation    represents the relationship between the two numbers.the equation    represents the sum of the two numbers.the number  d  is 14.the number  c  is 44.the number  c  is 14.the number  d  is 44.