Explanation:
First, you want to start by creating an equation to find the unit rate
calculators = c
9c = 96.30
Solve!!!
9c/9 = 96.3/9
c= 10.7
A calculator costs $10.70 (Sorry I will be using the dollar sign instead)
Now you want to set an expression for 13 calculators
13c
Substitute 10.7 in
13(10.7)
Multiply them
$139.10
13 calculators cost $139.10
I hope this helps!!!