Answer: Option 'B' is correct.
Step-by-step explanation:
Since we have given that ,
Total money he takes while going to the fair = $90
Money he spends to enter the fair = $5
Money he spends on food =$15
Total he spent now is given by
![\$5+\$15=\$20](https://tex.z-dn.net/?f=%5C%245%2B%5C%2415%3D%5C%2420)
Now, he spend on rides at the fair i.e. 1.50 per ride .
Let the number of rides be x
So, cost incurred on rides = 1.5x
So, the spending money can be expressed as
![20+1.50x](https://tex.z-dn.net/?f=20%2B1.50x)
Now, remaining money left to him after spending on x rides too is
![90-(1.50x+20)\\\\=90-1.50x-20\\\\=70-1.5x](https://tex.z-dn.net/?f=90-%281.50x%2B20%29%5C%5C%5C%5C%3D90-1.50x-20%5C%5C%5C%5C%3D70-1.5x)
Let f(x) denotes the function used to determine the money he has left over after rides .
So it becomes
![f(x)=70-1.50x\\\\f(x)=-1.50x+70](https://tex.z-dn.net/?f=f%28x%29%3D70-1.50x%5C%5C%5C%5Cf%28x%29%3D-1.50x%2B70)