Part A:
The question is a word problem and we develop the system in mathematical equations.
Lashonda went to the store 4 days a week.
Each day, she bought 1 sandwich and 1 comic book.
[tex]1sandwich=\text{ \$6}[/tex][tex]1\text{comic book = \$c}[/tex][tex]\begin{gathered} \text{Total spent on sandwich and comic book per day = \$}(6+c) \\ Total\text{ spent on sandwich and comic book per w}eek\text{ (4days) is = \$4(6+c)} \end{gathered}[/tex]
In 4days, in the week. she spent $36
[tex]\text{ \$4(6+c)=\$36}[/tex]
Therefore;
[tex]4(c+6)=36[/tex]
Part B:
To calculate the amount spent on each comic book, we find c.
From the equation derived in Part A, we make c the subject of the formula.
[tex]\begin{gathered} 4(6+c)=36 \\ E\text{ xpanding the bracket,} \\ 24+4c=36 \\ \text{Collecting the like terms,} \\ 4c=36-24 \\ 4c=12 \\ \text{Dividing both sides by 4,} \\ c=\frac{12}{4} \\ c=3 \\ c=\text{ \$3} \end{gathered}[/tex]
Therefore, the amount she paid for each comic book in dollars is $3.
