The average of 3numbers is 10 if the sum of the numbersis 9 what is the third number

Avg of 7 numbers = 9

Total of 7 numbers will be = 9 * 7 = 63

Avg of 3 of them is = 5

Total of those 3 will be = 3 * 5 = 15

Therefore the total of other 4 = 63 - 15 = 48

Ergo , avg of them = 48 / 4 = 12

Answer is 12

hope this helps!

to find the perimeter of the rectangle this is the expression:

x-9+x-9+3x-4+3x-4=138

if we simplify it:

8x-26=138

remember, 138 is what it all adds up to

the length is 11.5cm

the width is 57.5cm

the area is 661.25cm^2

the answers might not be correct use at own risk