Question 166720
Assume the student expected to make D dollars/hour and work for H hours.
That student expected to earn $24. So, {{{24 = D * H }}}
{{{24/H = D}}}

The problem tells you the student had to work longer for the same money. The student worked {{{H+1}}} hours and earned the same $24. The student  ended up getting {{{D-4}}} dollars per hour.

{{{24 = (D-4)*(H+1)}}}
Subbing in the expected return
{{{24 = (24/H - 4) (H + 1)}}}
{{{24 = (24 - 4H)/H * (H+1)}}}
{{{24H = (24-4H)(H+1)}}}
{{{24H = 24H - 4H^2 + 24 - 4H}}}
{{{4H^2 +4H -24 = 0 }}}
{{{H^2 +H -6 = 0}}}
{{{(H+3)(H-2)=0}}}
So the student expected to work 2 hours or -3 hours. Since one cannot work -3 hours, the student expected to work 2 hours at $12/hour. Instead, the student worked 3 hours at $8/hour. A difference of $4 per hour


As far as "how do I do word problems goes", look for pertinent info. Many problems will give you more data -- some of it may be irrelevant. This problem gave you only good data, and no more or no less than required to solve.

The "trick' in this one is to know that wages= WageRate * HoursWorked