Question 204094
{{{C[1] = 42+5x}}} where x = number of hours.
{{{C[2] = 8.5x}}}
You want to find, for what x is:
{{{C[1] < C[2]}}} Substitute from above:
{{{42+5x < 8.5x}}} Subtract 5x from both sides.
{{{42 < 3.5x}}} Divide both sides by 3.5
{{{12 < x}}}
Answer: 12 hours.