SOLUTION: sir what is (2x)/(3)-(7y)/(2)= -5 (5x)/(3)-(y)/(2)= 4?

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: sir what is (2x)/(3)-(7y)/(2)= -5 (5x)/(3)-(y)/(2)= 4?      Log On


   

Question 741688: sir what is (2x)/(3)-(7y)/(2)= -5
(5x)/(3)-(y)/(2)= 4?
Found 2 solutions by mananth, rothauserc:
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
%282x%29%2F%283%29-%287y%29%2F%282%29=+-5
LCM of the denominator is 6
%282x%2A6%29%2F%283%29-%287y%2A6%29%2F%282%29=+-5%2A6

multiply equation by 6

4x-21y=-30.................................(1)

%285x%29%2F%283%29-%28y%29%2F%282%29=+4
same way multiply eqation by 6
10x-3y=24...............................(2)
solve for x & y

Eliminate y
multiply (1)by 1.00
Multiply (2) by -7.00
4.00 x -21.00 y = -30.00
-70.00 x + 21.00 y = -168.00
Add the two equations
-66.00 x = -198.00
/ -66.00
x = 3.00
plug value of x in (1)
4.00 x -21.00 y = -30.00
12.00 -21.00 y = -30.00
-21.00 y = -30.00 -12.00
-21.00 y = -42.00
y = 2.00

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
We are asked to solve
(2x)/(3)-(7y)/(2)= -5
(5x)/(3)-(y)/(2)= 4
1) note that 3 * 2 = 6 is our common denominator, so we can rewrite
(4x/6) - (21y/6) = -5
multiply both sides of = by 6
4x - 21y = -30
2) 6 is also the common denominator here, so we rewrite
(10x/6) - (3y/6) = 4
multiply both sides of = by 6
10x - 3y = 24
solve 1) for x and we have x = (-30+21y)/4
substitute for x in 2)
10*((21y-30)/4) - 3y = 24
5*((21y-30)/2) - 3y = 24
(105y - 150)/2 - 3y = 24
105y - 150 - 6y = 48
99y = 198
y = 2
10x - 3*2 = 24
10x = 30 and x = 3