Question

a light switch works 25% of the time, how many times does it not work if switched on 64 times in a week

Answer 1

25% of 64 is 16
$\frac{25}{100} = \frac{x}{64} \\ x = \frac{64 \times 25}{100} = \frac{1600}{100} = 16$
it will work properly 16 times
$64 - 16 = 48$
it will not work 48 times
hope this helps