Answer:
-10
Step-by-step explanation:
-4 between each number
If T is the midpoint, then that means its exactly 1/2 of the way between 2 points
this means we can set the 2 given values equal
4x - 3 = 2x + 7
first move like terms to the same side
2x = 10
x = 5
now that we know the length of x, we plug it back in to get the length
4x - 3 + 2x + 7 = 6x + 4
6(5) + 4 = 34
Answer:

Step-by-step explanation:
the formula for density is:

where d is density, m is mass, and V is volume.
solving for m in the last equation:

so if we find the volume and multiply it by the density
we will get the mass of the object.
The volume of a rectangular prism is given by:

where
is length,
is width and
is height:

we substitute to find the volume:

since the density has units of
we need the volume also in units of
, so we make the conversion using:

multiplying by 30:

and now we find the mass with the equation:

substituting d and V:

the nearest gram is: 
(x + 7) - (3x + 4) = x + 7 - 3x - 4 = (x - 3x) + (7 - 4) = -2x + 3