how do i solve 3/4(x+2y)=z?

in terms of a variable?

3/4(x + 2y) = z
3(x + 2y)/4 = z
3(x + 2y) = 4(z)
3(x + 2y) = 4z
x + 2y = 4z/3
2y = 4z/3 - x
y = (4z/3 - x)/2
y = (4z/3)/2 - x/2
y = (4z/3)(1/2) - x/2
y = 2z/3 - x/2

all u have to do is solve for y so:
3/4(x+2y)=z
3/4x+3/4(2y)=z
.75x+1.5y=z
.75x-.75x+1.5y=z-.75x
1.5y=z-3/4x
1.5y/1.5=(z-.75x)/1.5
y=z/1.5-0.5x

3/4(x+2y)=z

distribute the 3/4 inside the parenthesis

3/4x + 1.5y = z

subtract 3/4x from both sides

1.5y = z - 3/4x

divide both sides by 1.5

y = 2/3z - 1/2x

it also equal 3x+6y=4z

For three variables you would need three equations.

you need more info. is x, y, or z equal to anything in the given information?

You can't solve this equation

it equals (3x+6y)/4=z