alg.
posted by j .
solve the system by addition:
5x9y = 5
x+5y=15
I've tried this one over and over, but I can't seem to get the right answer. I don't even really know where to start. each time i try to do it, i go about it a little differently and i'm completely lost, pls help!!
from the second equation:
x=5y15
now sub that back in the first one:
5(5y15)9y=5
25y+759y=5
16y=575
16y=80
y=5
now sub that back into x=5y15
x=5(5)15
x=2515
x=10
OR
first equation .....
5x  9y = 5
second equation times 5 ...
5x + 25y = 75
add them, the x's are eliminated
16y = 80
y = 5
substitute that in one of the originals, etc
Respond to this Question
Similar Questions

math
problem is solve for the unknown 2/3 over 10 = 1.8 over r dont even know where to start to solve this please help crossmuliply 2/3 r = 18 multiply both sides by 3/2 thank you 
Simplfing Fractions
Three problems I need to know if I am correct or not if not I will place how I got the answer and maybe some one can show me where I messing up aT Simplify 1+2/3 over top 2+1/2 My answer was 2/3 to me it does not seem right If I am … 
Algebra 2
would some one please check these for me 1. divide x^236y^2 over 5x^2+30y divide (x^26xy) A: x+6y over (5x)(x^2+6y) 2. Add. Express your answer in simplest form. 2x 0ver x^2+15x+54 + 4over x+6 A: 6 over x+9 3. solve: (9 over x5) … 
alg
if n+5n+3 over n3n5=16 what is the value of n this is an SAT question and i just cant seem to figure it out..even with pluggin in the numbers it never = 16...so help pls..what is the quickest way in solving this for the SAt's 
Math  help really needed
I'm sorry to double post; I don't want to seem impatient, but I really need help with this. Prove each idenity. 1+1/tan^2x=1/sin^2x 1/cosxcosx=sinxtanx 1/sin^2x+1/cos^2x=1/sin^2xcos^2x 1/1cos^2x+/1+cosx=2/sin^2x and (1cos^2x)(1+1/tan^2x)= … 
Algebra
x^336x over x^2+7x+6, divided by 6x^2x^3 over x^2+x I know the right answer is 1, but I can't seem to get to it. I've gotten as far as [x(x6)]/1] * 1/[x^2(6x)], which is then equal to [x(x6)]/x^2(6x). And then would I reduce … 
Math
3x2 over 2 (fraction format) x over 4 (fraction format) = 15. I know that I need a LCD but when I tried 2 it didn't seem to work right. the only hint my math teache gave was the answer has to be a mixed number. Can anyone help? 
College Chemistry
For my homework I got this problem that my professor never went over in class how to do it and I don't know how to interpret it. A chemist runs a second order reaction of A>B starting at 10mili moles/L concentration of A (and no … 
Math
if f(x) = 2x^2+4 and g(x)=x3 which number satisfies f(x)= (f o g)(x) A) 3/2 B) 3/4 C) 5 D) 4 I am positive that answer A is correct, i just cant get the work to prove it, i can disprove all other answers and my teacher has assured … 
Algebra
Solve the system of equations and check your solution. x^2+y^2=25 x+2y=10 I tried but I got only the 2 x values 8 plus or minus the square root of 164 all over 2. I know the answer is wrong but I can't find my mistake. Can you show …