Zakir travels from City A to City B. If Zakir drives his car at $$\frac 23$$​ of his normal speed, then he reaches City B 45 minutes late. Find the time (in minutes) that Zakir would have taken to travel from City A to City B if he drove at his normal speed.

Correct option is C

Given:

Let normal time taken = x minutes
Reduced speed = $$\frac 23$$​of normal speed
Time difference = 45 minutes
Formula Used:
Time = Distance / Speed
If speed is reduced, time increases in inverse ratio.
Solution:
If speed is $$\frac 23$$ of normal, then time taken will be$$\frac 32$$ of normal time.
So, increased time = $$\frac 32$$​ × x

Difference in time = $$\frac 32$$x - x = 45
​$$\Rightarrow \frac{3x - 2x}{2} = 45\\\Rightarrow \frac{x}{2} = 45\\\Rightarrow x = 45 \times 2 = 90\\$$​​
Therefore, Zakir would have taken 90 minutes at his normal speed. 
Alternate Solution:
As we know, time is inversely proportional to speed.
Let the usual speed of the person be 3x
Speed of the person after decreasing = 2x
Ratio of usual speed to after decreasing = 3x : 2x
Ratio of usual time to after decreasing = 2x : 3x
3x – 2x = 45
=> x = 45
2x = 2× 45 =90 min