8. -3= 6(x - 7) = 42 - 6x

5. 6(1 – 3x) = -36 - 4x

10. 5+ 4(x - 1) = 2x -9
what does x equal for all of them

5. x = 3

10. x=-5

I am unable to find the answer for 8. but i hope this helps.

Step-by-step explanation:

The system of equations which can be used to find the prices of blue and green marbles : 3·x + 5·y = 11  and  4·x + 2·y = 10

Step-by-step explanation:

Let the price of blue marble be $x and the price of green marble be y

Number of blue marbles bought by Johann = 3

Number of green marbles bought by Johann = 5

Total amount paid by Johann = $11

So, The equation for this is given by :

3·x + 5·y = 11 (1)

Number of blue marbles bought by Martha = 4

Number of green marbles bought by Martha = 2

Total amount paid by Johann = $10

So, The equation for this is given by :

4·x + 2·y = 10 (2)

Thus, The system of equations which can be used to find the prices of blue and green marbles : 3·x + 5·y = 11  and  4·x + 2·y = 10