X+2y-z=3
-2x-3y+z=-1
6x-3y-z=-7

|  x = -1     y = -4      z = 3

Step-by-step explanation:Solve the following system:

{x+2 y+4 z = 3 |     (equation 1)

x-y-2 z = -3 |     (equation 2)

3 x+z = 0 |     (equation 3)

Swap equation 1 with equation 3:

{3 x+0 y+z = 0 |     (equation 1)

x-y-2 z = -3 |     (equation 2)

x+2 y+4 z = 3 |     (equation 3)

Subtract 1/3 × (equation 1) from equation 2:

{3 x+0 y+z = 0 |     (equation 1)

0 x-y-(7 z)/3 = -3 |     (equation 2)

x+2 y+4 z = 3 |     (equation 3)

Multiply equation 2 by -3:

{3 x+0 y+z = 0 |     (equation 1)

0 x+3 y+7 z = 9 |     (equation 2)

x+2 y+4 z = 3 |     (equation 3)

Subtract 1/3 × (equation 1) from equation 3:

{3 x+0 y+z = 0 |     (equation 1)

0 x+3 y+7 z = 9 |     (equation 2)

0 x+2 y+(11 z)/3 = 3 |     (equation 3)

Multiply equation 3 by 3:

{3 x+0 y+z = 0 |     (equation 1)

0 x+3 y+7 z = 9 |     (equation 2)

0 x+6 y+11 z = 9 |     (equation 3)

Swap equation 2 with equation 3:

{3 x+0 y+z = 0 |     (equation 1)

0 x+6 y+11 z = 9 |     (equation 2)

0 x+3 y+7 z = 9 |     (equation 3)

Subtract 1/2 × (equation 2) from equation 3:

{3 x+0 y+z = 0 |     (equation 1)

0 x+6 y+11 z = 9 |     (equation 2)

0 x+0 y+(3 z)/2 = 9/2 |     (equation 3)

Multiply equation 3 by 2/3:

{3 x+0 y+z = 0 |     (equation 1)

0 x+6 y+11 z = 9 |     (equation 2)

0 x+0 y+z = 3 |     (equation 3)

Subtract 11 × (equation 3) from equation 2:

{3 x+0 y+z = 0 |     (equation 1)

0 x+6 y+0 z = -24 |     (equation 2)

0 x+0 y+z = 3 |     (equation 3)

Divide equation 2 by 6:

{3 x+0 y+z = 0 |     (equation 1)

0 x+y+0 z = -4 |     (equation 2)

0 x+0 y+z = 3 |     (equation 3)

Subtract equation 3 from equation 1:

{3 x+0 y+0 z = -3 |     (equation 1)

0 x+y+0 z = -4 |     (equation 2)

0 x+0 y+z = 3 |     (equation 3)

Divide equation 1 by 3:

{x+0 y+0 z = -1 |     (equation 1)

0 x+y+0 z = -4 |     (equation 2)

0 x+0 y+z = 3 |     (equation 3)

i use my brain for prombles like this maybe you could try it

step-by-step explanation:

for a it would be 24 children.

for b i don't understand the question. is it saying for each individual person they pick 5 reds to 7 greens or is it the whole group. clarify and i hope this can you.

step-by-step explanation: