One day a store sold 45 pens, the zippedy do's at $8.50 & The Royal Blues at $9.75. In all, $398.75 was spent on the pens. How many Royal Blues were sold that day?
45=Z+R
9.75R+8.5Z=398.75
R=45-Z
put that in for R in the second equation, and solve.
To find the number of Royal Blues pens sold, we need to set up equations based on the information given.
Let's assume x represents the number of Zippedy Do's pens sold and y represents the number of Royal Blues pens sold.
The first equation can be written as:
x + y = 45 (since the total number of pens sold was 45)
The second equation is based on the total cost of the pens:
8.50x + 9.75y = 398.75 (since the total cost of the pens sold was $398.75)
Now we have a system of two equations with two variables. We can solve it using different methods, such as substitution or elimination. Let's use the substitution method:
From the first equation, we can express x in terms of y:
x = 45 - y
Substitute this value of x into the second equation:
8.50(45 - y) + 9.75y = 398.75
Now, solve the equation for y:
382.5 - 8.50y + 9.75y = 398.75
(9.75y - 8.50y) = 398.75 - 382.5
(1.25y) = 16.25
y = 16.25 / 1.25
y = 13
Therefore, 13 Royal Blues pens were sold that day.