Question 888287
In the future, please list these as separate problems.  They'll get answered a lot more quickly.  Thank you.

1) 12G + 12S = 24*600
12G + 12S = 14400
S = 2G
Substitute the value of S into the top equation
12G + 12(2G) = 14400
12G + 24G = 14400
36G = 14400
Divide each side by 36
G = 400
If a goat costs 400, then a sheep costs 800
Price for 3 goats and 2 sheep = 3(400) + 2(800), or 1200+1600, or 2800

2) A + B + C = 600*3, or 1800
B + C + D = 750*3, or 2250
D = 900
Therefore, B + C = 2250-900, or 1350
Since A + B + C = 1800, subtract B+c (1350) to get A = 450

3) 34