Can you please help me solve questions 18 and 20 by using substitution or elimination method.
http://img230.imageshack.us/img230/4372/mathyv1.jpg
Thanks
here are the questions:
1)You are starting a business that sells air filters for homes. Your startup costs for the business are $1250 and each air filter kit costs $40.
If you sell the filters for $60, how many must you sell to break even?
2)If you buy 7 hmaburgers and 3 slices of pizza from Sizzler, you get $1 change from $20 bill. If you buy 8 hamburgers and 2 slices of pizza, you get $0.50 back from a $20 bill. How much change would you get from a $20 bill if you bought 3 slices of pizza and 5 hamburgers?
Thanks again!
I will use "substitution" since I believe that's what your teacher wants...
The amount of money you pay equals $1250 plus $40 per filter.
y=the amount of money
x=filters
Thus you have equation: y=40x+1250
The amount of money you make is equal to $60 per filter: y=60x
To braek even, the amount of money you make must equal the amount of money you spent, thus: 40x+1250=60x
now subtract both sides by 40x: 1250=20x
Now divide both sides by 20: 62.5=x
So you need to sell 62.5 filters to break even, which you can't do, so you sell 30 filters to break even.
7h+3p=192)If you buy 7 hmaburgers and 3 slices of pizza from Sizzler, you get $1 change from $20 bill.
Solve for p to get: p=(19-7h)/3
8h+2p=19.5If you buy 8 hamburgers and 2 slices of pizza, you get $0.50 back from a $20 bill.
Solve for p to get: p=(19.5-8h)/2
Substitute: (19-7h)/3=(19.5-8h)/2
solve for h, then substitute that value into one of the equations to find the price of hamburgers, than subtract the price of 3 slices of pizza and 5 hamburgers from 20.