Question 1209350
<br>
Working the problem "forwards", as shown in the other responses, requires doing some back-substitution to get the final answer.<br>
You can get the answer directly by working the problem backwards.<br>
He finished with $15.40 after spending $2.80 more than half of his money on school socks.<br>
let x = amount he had before buying the socks
{{{x-((1/2)x+2.80)=15.40}}}
{{{(1/2)x-2.80=15.40}}}
{{{(1/2)x=18.20}}}
{{{x=36.40}}}<br>
Before buying the socks, the amount he had was $36.40.  That was what he had after spending $12.20 less than half his money on stationery.<br>
let y = amount he had before buying the stationery
{{{y-((1/2)y-12.20)=36.40}}}
{{{(1/2)y+12.20=36.40}}}
{{{(1/2)y=24.20}}}
{{{y=48.40}}}<br>
The amount he had before buying the stationery was $48.40.  That was what he had after spending $8 more than 1/3 of his money on textbooks.<br>
let z = amount he had before buying the textbooks (i.e., the amount he had at first)
{{{z-((1/3)z+8)=48.40}}}
{{{(2/3)z-8=48.40}}}
{{{(2/3)z=56.40}}}
{{{z=84.60}}}<br>
ANSWER: The amount he started with was $86.40<br>