Answer: (b)
Step-by-step explanation:
Given
Function for bill calculation is
[tex]\Rightarrow b(x)=\left \{ {{0.15x\quad \quad \quad \, \ \ \ \ x<200} \atop {0.1(x-200)+30\quad x>200}} \right.[/tex]
The consumption is 700 kWh i.e. more than 200
Therefore, bill is given by the second function i.e. [tex]0.10(x-200)+30[/tex]
Substitute 700 for x to get the bill
[tex]\Rightarrow 0.1(700-200)+30\\\Rightarrow 50+30=\$80[/tex]
Hence, option (b) is correct.