Hello from MrBillDoesMath!
Answer:
The first choice ( -12, 20)
Discussion:
Using matrix multiplication we find the equations:
1x + 1y = 8 (A)
2x + 3y = 36 (B)
Next, compute
2(A) - B =>
(2x + 2y) - (2x + 3y) = 2*8 - 36 =>
(2x - 2x) + ( 2y-3y) = 16 - 36 =>
-y = -20 =>
y = 20
Substituting this y value in (A) gives
x + 20 = 8 =>
x = 8 - 20 =>
x = -12
The answer is the first choice ( -12, 20)
Thank you,
MrB
I'm so sorry for not answer but which grade and what workbook is it?
Hi I did my working on paper. You can see it in the photo.
divide total cost by length:
0.76 / 3ft = 0.2533 cents per foot
rounded to nearest cent = 0.25 cents per foot
Box 1 : 2
Box 2: 3
Box 3: 6
