Question 535696
You have the cost equations for both situations, so set these two equations equal to each other and solve for x.
{{{y = 2x}}} and
{{{y = x+10}}} Set these equal.
{{{2x = x+10}}} Solve for x. Subtract x from both sides.
{{{x = 10}}}
The monthly cost, y, will be the same if you use the bridge 10 times.
{{{2(10) = 10+10}}}
{{{20 = 20}}}