8th grade math please help

Answer: [tex]\bold{a)\quad E=\dfrac{1}{5}s}[/tex]
b) 75
c) $24
Step-by-step explanation:
the difference in the y-values (electricity) divided by the difference in the x-values (students) is the rate of change. [tex]\dfrac{10}{50}=\large\boxed{\dfrac{1}{5}}[/tex]
Electricity = rate of change × students ⇒ [tex]E=\dfrac{1}{5}s[/tex]
b) Find s when E = 15
[tex]15=\dfrac{1}{5}s\\\\\\(5)15=(5)\dfrac{1}{5}s\\\\\\\large\boxed{75 = s}[/tex]
c) Find E when s = 120
[tex]E=\dfrac{1}{5}\times 120\\\\\\E=\dfrac{120}{5}\\\\\\\large\boxed{E=24}[/tex]