Using order of operations, the answer is 569.
Answer is: 50.4%. You have to take 30% off of 72%. Easiest way is to find 10% of 72 (7.2) and multiply that by 3 (=21.6). Then minus this off the original price (72 - 21.6 = 50.4)
Do you remember when you were learning about
Least Common Multiple (LCM) ? And you were
wondering what on Earth you would ever need it for ?
THIS IS IT !
The amount of time after 8 PM when the lights will flash
together again is the LCM of 20 seconds and 30 seconds.
Do you remember how to find it ?
... When 20 is prime-factored, you have 2 · 2 · 5 .
... When 30 is prime-factored, you have 2 · 3 · 5 .
... So the Least Common Multiple of 20 and 30 is 2 · 2 · 3 · 5 = 60 .
The lighthouses will flash together again in 60 seconds after 8 PM.
That'll be 8:01 PM.
This can be written as (x+4)(x+4)
Multiply everything in the second parenthesis by the x.
x^2 + 4x
Multiply everything in the second parenthesis by 4.
4x + 16
Add these two equations together.
x^2 + 4x + 4x + 16
Combine like terms.
x^2 + 8x + 16
Hope this helps!
