8x + 7y = 25
x = 25 - 4y
2007-09-09 11:23:20 · 4 answers · asked by Anonymous in Education & Reference ➔ Homework Help
8(25-4y) + 7y = 25
200 - 32y + 7y = 25
-25y = -175
y = 7
x = 25 - 4(7)
x = 25 - 28
x = -3
2007-09-09 11:29:24 · answer #1 · answered by penguin 1 · 0⤊ 0⤋
8x + 7y = 25
x = 25 - 4y
Substitute for x in equation #1:
8(25 - 4y) + 7y = 25
Solve for y, remove brackets:
200 - 32y +7y = 25
Subtract 200 both sides:
-25y = -175
y = 7
Substitute in equation #2:
x = 25 - 4(7)
x = 25 - 28
x = -3
Proof: using equation #1
8(-3) + 7(7)
-24 + 49
25 = right side
2007-09-09 11:35:42 · answer #2 · answered by Robert S 7 · 0⤊ 0⤋
I hope that you tried the question .Here'e some help
Substitution here means that you make one of the letters the subject in one equation then substitute it in the second one
HINT: x is already the subject .
Sub. x=25-4y in
8x +7y =25
8(25-4y)=25
Multiply the brackets you'll find y
Then substitute y in the equation x=25-4y and you will find x
2007-09-09 11:31:58 · answer #3 · answered by Kay B 3 · 0⤊ 0⤋
8x+7y=25 x= 25-4y
8(25-4y)+7y=25
200-32y+7y=25
200-25y=25
-25y over -25 = -175 over -25
y=7
2007-09-09 11:31:39 · answer #4 · answered by xbellababeeo@snet.net 1 · 0⤊ 0⤋