Answer:
54 cents
Step-by-step explanation:
The cost of bookmarks relating to the number of bookmarks is given by the graph shown. Therefore:
From the graph, we can determine the relationship between the cost of bookmarks and the number of bookmarks by using two points. The equation of a line passing through points [tex](x_1,y_1)\ and\ (x_2,y_2)[/tex] is:
[tex]y-y_1=\frac{y_2-y_1}{x_2-x_1} (x-x_1)\\[/tex]
From the graph, y represents the cost of bookmarks in cents and x represent the number of bookmarks. we can see that it passes through the point (2, 30) and (7, 90). Hence:
[tex]y-30=\frac{90-30}{7-2}(x-2)\\\\y-30=12(x-2) \\\\y-30=12x-24\\\\y=12x+6[/tex]
The cost of 4 bookmarks (x = 4):
y = 12(4) + 6
y = 54 cents
