Answer:
[tex]103\ notebooks[/tex]
Step-by-step explanation:
The question in English is
Martha spent $60 to buy the same notebooks if each notebook had cost $2 plus Martha would have bought 80 fewer notebooks for the same $60. How many notebooks did Martha buy?
Let
x -----> the cost of each notebook
n -----> number of notebooks that Marta bought
we know that
[tex]nx=60[/tex] -----> [tex]n=\frac{60}{x}[/tex] -----> equation A
[tex](n-80)(x+2)=60\\\\nx+2n-80x-160=60\\\\n(x+2)-80x=220 ---> equation\ B[/tex]
substitute equation A in equation B and solve for x
[tex]\frac{60}{x}(x+2)-80x=220[/tex]
Multiply by x both sides to remove the fraction
[tex]60(x+2)-80x^2=220x[/tex]
[tex]60x+120-80x^2=220x[/tex]
[tex]-80x^2-160x+120=0[/tex]
Using a graphing tool
Solve the quadratic equation
The solution is
x=$0.581
see the attached figure
Find the value of n
[tex]n=\frac{60}{0.581}=103\ notebooks[/tex]
