The mean of a, b,c, and d is 9 and the mean of a, b,c, d,e and f is 12. find the mean of e and f

mean of e + f = 18

Step-by-step explanation:

(a + b + c + d)/4 = 9         Multiply by 4

a + b + c + d = 9 * 4 = 36

(a + b + c + d + e + f ) / 6 = 12

but a + b + c + d = 36

(36 + e + f)/6 = 12             Multiply by 6

36 + e + f = 72                 Subtract 36 from both sides

e + f = 36                         Divide by 2 to find the mean.

(e + f)/2 = 36/2

mean of e + f = 18

you didn't give me the choices, so i will just give you the graph so you can look at your choices and choose the right one.

the first option is the answer.