They use percents less than one to get the the exact number
Peter's account is 910-40x, and Marla's account is 470-2x. This is a system, so you must find the number that makes both equations end up with the same number. Basically trial and error. Here is what I did:
Let's try the number 10. 910-400=510 and 470-20=450. I need a higher number.
Let's try 13 next. 910-520=390 and 470-26=444. Now the number has to be lower.
Let's try 12. 910-480=430 and 470-24=446. Close, and a little lower.
11.5 is too low, and 11.7 is too high. 11.6 has Equation 1 at 446 and Equation 2 at 446.8. Very close!
It is somewhere around 11.6. I hope that this can give you a start in figuring it out, because I don't believe in giving the complete answer, because then you do not learn anything from it.
#3
2 and three are supplementary angles .
#4.
The answer is opposite angles .
#5
Bisected angles are equal
Now
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On your calculator your write 8 on the y axis and 4 on the x axis
3 apples are to be divided up amongst 4 friends. 3/4 = 0.75 apples per person.