currently, you have $60 and your sister has $135. Yoiu decide to save $5 of your allowance each week, while your sister decides to spend her whole allowanceplus $10 each week. how long will wit be before you have as much money as your sister? and i also need a equation view, and equation solved please
2006-10-03 17:47:42 · 5 answers · asked by NABEELiOS 1 in Science & Mathematics ➔ Mathematics
60+5N = 135-10N.
2006-10-03 17:50:32 · answer #1 · answered by Anonymous · 1⤊ 0⤋
You:
You start with $60
You save $5 a week and in x weeks you'll have $135
So y = 60 + 5x is your equation
Sister:
She starts with $135
We don't know how much allowance she gets, just that she spends it as soon as she gets it so it doesn't matter, it's not part of the equation.
She spends $10 of the $135 each week, so in x weeks she'll have the same amount as you.
y= 135-10x
These systems of equations can be thought of like streets.
One street is y = 60 + 5x
The other is y = 135 - 10x
Where they cross is the intersection..just like on real streets. At this point both the streets are the same. Looking back at the equations, at the intersection, the equations are equal, sooo...
60 + 5x = y = 135-10x
60 + 5x = 135 - 10x <--now we have one variable and solve for it
-60 -60
5x = 135 -10x -60
+10x +10x
5x + 10x = 75
15x = 75
x = 75/15
x = 15/3
x = 5 weeks
We can check this by plugging x in to both equations and being sure they equal eachother.
2006-10-04 01:04:57 · answer #2 · answered by minuteblue 6 · 0⤊ 0⤋
OK... let x be the number of weeks that have gone by.
You start with $60 and add $5/week, so the amount of money you have equals 60 + 5x.
Your sister starts with $135 and subtracts $10/week, so the amount of money she has equals 135-10x.
When are the two equal? When 60+5x equals 135-10x.
60+5x = 135 - 10x
Move your x'es to the left side and numbers to the right:
5x + 10x = 135 - 60
15x = 75
x = 5
In five weeks, the two of you will have the same amount of money. I trust that makes sense to you :-)
2006-10-04 01:05:06 · answer #3 · answered by Bramblyspam 7 · 0⤊ 0⤋
y=5x+60
y=-10x+135
-10x + 135 = 5x +60
15x = 75
x = 5 weeks
2006-10-04 00:52:00 · answer #4 · answered by fleisch 4 · 0⤊ 0⤋
like this below in a long drawn out way
first week- $65 $125
2nd---------- 70 115
3rd----------- 75 105
4th ---------- 80 95
5th----------- 85 85
2006-10-04 00:55:30 · answer #5 · answered by Josh 2 · 0⤊ 0⤋