The total cost, 'C' is the sum of the cost of the notebooks, 'n' and the cost of the pencils. 'p': [tex] C=n+p [/tex]
The notebooks cost $2.55 each so for 4 notebooks we have: [tex]n=4 \times \$2.55[/tex]
The cases of pencils cost $1.99 each so for 3 cases we have: [tex]p=3 \times $1.99[/tex]
Substituting into our main equation we have: [tex]C=n+p[/tex] [tex]C=4(2.55)+3(1.99)[/tex] [tex]C=10.20+5.97[/tex] [tex]C=16.17[/tex]
Now that we know the total cost we can find the amount of change by subtraction from the total amount she has: [tex]Change=Total-Cost[/tex] [tex]Change=\$20.00-\$16.17[/tex] [tex]Change=\$3.83[/tex]
