When using a graph to solve equations, remember the following important rules:

A point on the graph represents both an x value and a y value. Reading the point off the graph can give you an answer for either value.
To read between points on a graph, it is helpful to sketch a line between them to help estimate the correct answer.
To use the graph to predict something that hasn't happened yet, connect the data points with a line that extends beyond the data, and use that line to make your prediction.

Much like with graphs, some solutions to problems can be read directly from data tables, while others can be found by using a pattern set by the table.

When working with problems involving equations, you can determine solutions by substituting a known value into the equation and then using mathematical operations to calculate a result.

Based on what you have learned from this lesson, read and solve the following problem. Click each hint button if you need help.

Marco is making cookies for a fundraising bake sale at school. The recipe makes 3 dozen cookies and calls for 2 cups of sugar. How many cups of sugar will Marco need if he wants to make 7 dozen cookies?

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Graph Hint

graph of cups of sugar vs. number of cookies with upward sloped line and points at (3, 2), (6, 4) and (9, 6)

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Table Hint

Cookies (dozens)	Sugar (cups)
3	2
6	4
7	s
9	6

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Equation Hint

The equation that could be used to calculate s, the amount of sugar to make c dozen cookies is:
s = 2 over 3 2 3 c
Substitute 7 for c and solve.

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Check Your Answer

c = 42 over 3 2 3 cups