Question 352947
Let C = total cost of renting the van.  This is the dependent variable.
Let x = number of miles the van was driven.  This is the independent variable.

Then {{{C = 0.031*x + 87}}}.
If {{{C = $275}}}, then {{{275 = 0.031*x +87}}}.
{{{275-87 = 0.031*x}}}
{{{188 = 0.031*x}}}
{{{x = 6064.52}}}miles.

If {{{x = 1358}}}
{{{C = 0.031*1358 +87 = 129.10}}}$.