After taking 5 quizzes, your average is 76 out of 100. What must your average score be on the next five quizzes to increase your average to 81?
A. 78
B. 87
C. 83
D. 86

Option D

86

Step-by-step explanation:

When your expectation is average of 81 for a total of 10 questions, your total score is 10*81=810

Currently, for 5 questions with an average of 76, your total score is 5*76=380

Difference between total expected score and current score is 810-380=430

Average of difference with 5 questions is 430/5= 86

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

english maybe i can ..