0.25 r – 0.125 + 0.5 r = 0.5 + r . solve for r

First, we need to get all of the r's on the same side.  To do this, we need to subtract "r" from both sides.

0.25r - 0.125 + 0.5r - r = 0.5 + r - r

0.25r - 0.125 +0.5r - r = 0.5

Now, we need to add like terms.

0.25r + 0.5r - r - 0.125 = 0.5

-0.25r - 0.125 = 0.5

Now, we need to get the "r" variable by itself.

-0.25r - 0.125 + 0.125 = 0.5 + 0.125

-0.25r = 0.625

Now, we divide both sides by -0.25

(-0.25r) / (-0.25) = 0.625 / (-0.25)

r = -2.5

C. expression because any expression or equation may contain more than one variable