Answer:
6
upgraded phones were sold on Tuesday
Explanation:
Here, we want to know the number of upgraded phones sold by the company on Tuesday;
From the question, we are told that the company made $1,800 in sales on Tuesday;
Let the number of basic phones sold be x while the number of upgraded ones sold be y
Revenue from the basic ones would be 60 * x = 60x
Revenue from the upgraded ones will be 200 * y = 200y
By adding both, we will have the total sales;
60x + 200y = 1800 •••••••(i)
Also we are given the amount that the company paid to get these phones;
Cost of basic = 10 , so cost of x basic = 10 * x = 10x
Cost of upgraded = 50, so cost of y upgraded = y * 50 = 50y
Adding both;
10x + 50y = 400 •••••(ii)
So we have two equations to solve;
From ii, 10x = 400-50y
we can rewrite equation 1 as follows;
6(10x) + 200y = 1800
Substitute 10x = 400-5y into equation ii
6(400-50y) + 200y = 1800
2400 -300y + 200y = 1800
2400 -100y = 1800
100y = 2400-1800
100y = 600
y = 600/100
y = 6
This means 6 upgraded phones were sold on Tuesday