Choose a random number between 1 and 20. What is
the probability that the
number is greater than 5
and less than 15
Oh

There is 20 numbers total. Between 5 and 15, there is 10 numbers. But to be greater than 5 you’d count 6, 7, 8, 9, 10, 11, 12, 13, and 14 to still be less than 15. This means there is 9 numbers out of 20 that could fit within your numerical range. This is written as 9/20, 0.45 or 45%

If it’s greater than 5 and less than 15 with those numbers included then it would be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15. This would be written as 11/20, 0.55 or 55%

I hope this helps.

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.