Final answer:
To write the system of equations, we can define variables for the number of calculators and calendars ordered. We can then use the substitution method to solve the equations and determine the number of calculators and calendars ordered.
Step-by-step explanation:
To write the system of equations, we need to define some variables:
Let x be the number of calculators ordered
Let y be the number of calendars ordered
Based on the given information, we can create the following equations:
x + y = 80 (equation 1)
10x + 15y = 1000 (equation 2)
Using the substitution method, we can solve the system of equations by solving equation 1 for x:
x = 80 - y
Substituting this expression for x into equation 2:
10(80 - y) + 15y = 1000
800 - 10y + 15y = 1000
5y = 200
y = 40
Substituting this value of y into equation 1 to solve for x:
x + 40 = 80
x = 40
Therefore, 40 calculators and 40 calendars were ordered.