I need help with this question

Answer:
[tex]c = \frac{1}{4}m+ 15[/tex]
Step-by-step explanation:
Given
The attached graph
Required
The graph equation
Pick two points from the graph, we have:
[tex](m_1,c_1) = (0,15)[/tex]
[tex](m_2,c_2) = (40,25)[/tex]
Start by calculating the slope (a)
[tex]a = \frac{c_2 - c_1}{m_2 - m_1}[/tex]
So, we have:
[tex]a = \frac{25 - 15}{40 - 0}[/tex]
[tex]a = \frac{10}{40}[/tex]
[tex]a = \frac{1}{4}[/tex]
The equation is then calculated using:
[tex]c = a(m - m_1) + c_1[/tex]
So, we have:
[tex]c = \frac{1}{4}(m - 0) + 15[/tex]
[tex]c = \frac{1}{4}m+ 15[/tex]