If the average of x and y is 11 and the average of x, y and z is 5, what is the value of z? ​

z = -17

Step-by-step explanation:

If the average of x and y is 11, then;

x+y/2 = 11

x+y = 2 + 11

x+y = 22 1

similarly, if average of x, y and z is 5, then;

x+y+z/3 = 5

x+y+z = 3*5

x+y+z = 15

Since x+y = 22

22 + z = 5

z  = 5 - 22

z = -17

Hence the value of z is -17

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!

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step-by-step explanation: