3kids are splitting up 192 pieces of candy. jeff will get 3/4 of what gabe gets, and sadie will get three times as much as jeff how many pieces of candy does each kid get?

First define your variables in terms of one variable.

J = amount of candy for Jeff = 3/4G
G = amount of candy for Gabe 
S = amount of candy for Sadie = 3J = 3(3/4G)=9/4G

Create an equation. J + G + S = 192
Substitute. 3/4G + G + 9/4G = 192
Clean up. 12/4G+G=192
3G+G=192
4G = 192
G=48

Find the other values.
G = 48
S = 9/4G = 9/4(48) = 108
J = 3/4G = 3/4(48) = 36

Ok here we go ..there are plenty of ways to solve such math problems but we will go for the smartest and easiest ..5x+2y=7  -2x+6y=9we rearrange them into the following ..by multiplying the 1st equation by 2 it becomes 10x + 4y = 14we rearrange it and so it becomes 10x = 14 - 4yas for the second equation we multiply it by 5 and rearrange it so it becomes as to the following ..-10x + 30y = 45rearranging so 10x = 30y -45now 10x equals both 14 - 4y and 30y -45so   14 - 4y = 30y -4531 = 26yy= 31/26 = 1.19 or around 1.2so by now we can calculate x easily as  -2x+6y=9so 2x = 6y -9 = 6 * 31/26 - 9 = -1.84  then x = - 0.92 or around -0.9best luck!