What is the meaning effiency 85% of simple machine​

Why are radio observatories located in valleys far away from urban centers? a. to shield them from electromagnetic interference b. to avoid sound pollution c. to avoid disturbing people living in the city d. to shield them from water vapor

Question 1(multiple choice worth 10 points)} stefan sees a commercial on television that makes him think he needs to buy an e-reader. this is an example of wasting time getting distracted allowing someone to set goals

Mrs. foyle told yolanda that her test had 38 problems worth a total of 100 points. each test problem is worth either 5 points or 2 points. yolanda wanted to determine how many 2-point and how many 5-point questions are on the test. in the space below, determine how many questions of each point-value are on the test. show your work or provide an explanation to support your answer. need this asap