Answer :

The best thing to do us to find the difference between $150 and $100. The difference is $50. You've then got to divide $150/$50 and thus gives you 3.333, therefore, the percentage decrease is 33% Hope this helps :)
n/100*150=100

150n=10,000

n=10,000/150

=(1,000*10)/(15*10)

=1,000/15

=200/3

=66+2/3

$100 is approximately 66.6% of $150, therefore the percent decrease was approximately 33.3%.