Answer:
54 cents
Step-by-step explanation:
The cost of bookmarks relating to the number of bookmarks is shown in the coordinate grid. x represents the number of bookmarks and y represents the cost of each bookmark in cents.
The equation of a line passing through the points [tex](x_1,y_1)\ and\ (x_2,y_2)[/tex] is given by:
[tex]y-y_1=\frac{y_2-y_1}{x_2-x_1}(x-x_1)[/tex]
From the coordinate grid, it has the points (2, 30) and (7, 90). Therefore, the equation is:
[tex]y-30=\frac{90-30}{7-2}(x-2)\\\\y-30=12(x-2)\\\\y-30=12x-24\\\\y=12x+6[/tex]
Therefore the cost of 4 bookmarks (x = 4):
y = 12(4) + 6
y = 48 + 6
y = 54 cents
