Answer:
it's 8
Step-by-step explanation:
just get 72 and divide it by 9 and that's the average over the 9 years.
Answer:
Step-by-step explanation:
x-y=7
-3x+9y=-39
Divide the second equation by 3
-x +3y = -13
Add this to the first equation
x-y=7
-x +3y = -13
----------------------
0x +2y = -6
Divide by 2
2y/2 = -6/2
y = -3
Now find x
x-y = 7
x -(-3) = 7
x+3 = 7
Subtract 3 from each side
x = 4
(4,-3)
Or by substitution
x-y=7
solve for x
x = 7+y
-3x+9y=-39
Substitute y+7 in for x
-3(7+y) +9y = -39
Distribute
-21 -3y +9y = -39
Combine like terms
-21 +6y = -39
Add 21 to each side
6y = -18
X= weight of TV
y= weight of CD
3x+5y= 62.5
3x+ 2y= 52
You can either solve for a variable, or eliminate a variable by subtracting the second equation from the first:
3x + 5y = 62.5
-(3x+2y = 52)
0 + 3y = 10.5, so y = 10.5/3 or 3.5.
Now plug y= 3.5 back into any equation to get x:
3x + 5(3.5) = 62.5
3x + 17.5 = 62.5
3x = 45
x = 15
Always check work. Both equations should be true for x=15, y= 3.5
