Math homework I need help

[Luizao876]

I suck in proportions, so if anybody here can help, I will be grateful.

Here are the questions ( the ?/? are fractions):

B) m/15 = n/6, m - n = 90
C) r/s = 13/5 , r - s = 72
D) 18/x = 8/y, x + y = 104
E) x/8 = y/3 = z/4, x - y + z = 108
F) 15/x = 9/y = 3/z, x - y - z = 42

This is middle school stuff I think, so it shouldn't be so hard to solve them if you are good in Math. I will be grateful for whoever does this for me.

[Desu]

I'm too lazy to do these right now, but, the general way you do these is:

1) rearrange the proportions such that you get the variables in the numerator.
2) on the right side, (m-n = 90 etc.) solve for one variable
3) use that information and put it into the proportion

like for B)
m-n = 90
m = 90 + n

Therefore,

substitute m = 90 + n for m
(90 + n) / 15 = n / 6

dive 90 + n by 15
6 + (n / 15) = n / 6

subtract n / 15 from both sides
6 = (n / 6) - (n / 15)

Solve for n. Once you have n, put n back into the original equation you start with, then solve for m.

[Luizao876]

Thanks for the help Desu, I was able to finish all of the homework.

[Heil_Kaiba8921]

freaking smart-ass middle schools...this is what we were learning last semester and i sucked at them because the teacher was dull, demanded respect and never gave you any, and literally put me to sleep even if i was wide awake.

I ended up getting a 57% in his class so i'm in the repeat class for algebra 2 with a better teacher (i know because i had him before and used to go to him all the time for help during study hall)...i do wish that i would have worked just slightly harder to be able to have passed first semester

[SmokeyTheAggie]

I solved F for ya. x = 210, y = 126, z = 42