SOLUTION: solve x+4y=19 5x+y+0 solve a-b=25 3a+4b=4

Question 385320: solve
x+4y=19
5x+y+0

solve
a-b=25
3a+4b=4
Answer by texttutoring(324) (Show Source): You can put this solution on YOUR website!
x+4y=19
5x+y+0
Let's solve this one by elimination method. Multiply the second equation by 4, then subtract it from the first equation:

x+4y = 19
20x +4y = 0
-----------
-19x = 19

x= -1

Plug this value into either equation to find y:
5x+y = 0
5(-1) + y = 0
-5 + y = 0
y = 5

So the solution is (-1,5) or x=-1, y=5.

Second question is weird because it has no nice answers. Are you supposed to write your answers as fractions or as decimals? I did it with fractions:

a-b=25
3a+4b=4
Multiply the first equation by 3, then subtract.

3a - 3b = 75
3a + 4b = 4
--------------
0 - 7b = 71

b = -71/7

Plug this into either equation to find a:

3a - 3(-71/7) = 75
3a + 213/7 = 75
3a = 75- 213/7
3a = 312/7
a = 312/21
a = 104/7
RELATED QUESTIONS
Solve each system of equations. If no solution explain why! Substitution method x-y=3 (answered by Alan3354)

Can you help me solve these equations using the substitution method? 1) x-y=15; y=-4x (answered by ankor@dixie-net.com)

Solve each system by substitution. Show your work. 1) a= 3b+1 5a-3b= 13 2) 4y=... (answered by Edwin McCravy)

Plz solve 2a-[3b-{4b-(b-a-3a+4b)}] And bar is on... (answered by Alan3354)

3a-4b=-22 -3a+b=0 solve by substitution!! i need... (answered by Fombitz,vleith)

How do you solve 6x+y=4... (answered by josgarithmetic,ikleyn)

how do I solve 5x-3y+3a when x=6 and y and a =7 (answered by vheroli)

1) v=r+at, solve for a 2) y=mx+b, solve for m 3) I=prt, solve for r 4) by+2/3=c, solve (answered by rahman)

the problem is: 3a-4b=1 12a-b= -11 this is as far as i have gotten... 3a-4b=1 (answered by RAY100)