Take -5x + 3x = -2x
because there is a -3x and a 3x they cancel each other out.
and the -17 is left
-2x = -17
divide -2 by -17 = 8.5
Multiply 54 times 100 then divide by 1,762
54 times 100= 5400
5400\1,762= .03
which equals to 3%
When calculating probability you need to remember that probability is:
something that you are observing divided by total number of participants.
The number you get is relative value(has value between 0 and 1) and if you want to get it in percentage (more clearly) just multiply it with 100.
In this case we are observing blood type B persons. Number of them is 165.
Total number of persons is 1500. Therefore our calculation looks like this:
165/1500 = 0.11 or the probability is 0.11*100=11%