Why? Jeff told you that 2x + 4y = 74. (His x and y are in cents, yours apparently in dollars which owould give you 2x+ 4y= .74.) That is not the same as "x= .74+ y".
x+6=1.53(y+5) uummmmmm ex-1 { x+y= } prentice hall classic algebra 1
I have no idea what this means.
Okay, now this is what Jeff suggested.
{ x-y= } try this (E) pg 375
You can't just take equations from
other problems and expect them to work for this problem!
Okay, this is "6 pens and 5 pencils cost $1.53"
Again, I don't know what "x+ y= " has to do with this. And where did "n" come from??
I
think you are subtracting each side of 4x+ 2y= .74 from 6x+ 5y= 1.53. Yes, (6x+ 5y)- (4x+ 2y)= 2x+ 3y. But 1.53- .74= .79, not .78. But what was your purpose in doing that? You ought to be trying to eliminate one of "x" or "y"?
hhhmmm ex-3 x=n+y
x+n=n(y+n)
ok 6+5=1.53 (x+y=1.53)
again, where did this "n" come from? What does it mean?
Of course, "6+ 5" is NOT equal to "1.53"! You meant 6x+ 5y= 1.53. That is NOT the same as "x+ y= 1.53". I don't know where you got that.
You seem to be just putting numbers and letters together pretty much at random! Use some logic. You did, finally get the two equations:
"
four pencils and two pens cost $.74": 4x+ 2y= .74
:six pencils and five pens cost $1.53. find the cost of a pencil and a pen": 6x+ 5y= 1.53.
Just subtracting one from the other doesn't help. You need to have a reason for doing things like that. If you multiply the first equation by 3, you get 12x+ 6y= 2.22. If you multiply the second equation by 2 you get 12x+ 10y= 3.06.
My "reason" for doing that was to get the same coefficient for x in both equations. Now you can subtract one equation from the other- because each equation has "12x", those will cancel: (12x+ 10y)- (12x+ 10y)= 2y= 3.06- 2.22= 0.84.