So x + y = 45, and 4x + 5y = 195. Get y by itself. Subtract x from both sides in the first equation to get y = 45 -x, and subtract 4x from the second equation to get 5y = 195 - 4x. Divide by 5 to both sides to get y = 39 - 4/5x. 39 - 4/5x = 45 - x. Add x to both sides to get 39 - 1/5x = 45. Subtract 39 from both sides to get -1/5x = 6. Divide by -1/5 to get x = -30, or 30. In the first equation, do 30 + y = 45. Subtract 30 from both sides to get y = 15. Check. 4(30) + 15(5) = 195, or 120 + 75 = 195.
Answer:
Eudora ran for 30 minutes and use the jetpack for 1 hour and 30 minutes
Step-by-step explanation:
Lets call x the time she ran and y the time she was using a jetpack (in hours), we have
12x + 76y = 120
Since it took 2 hours we have that x+y = 2, hence y = 2-x. We can replace y in the equation above, obtaining
12x + 76(2-x) = 120
12x+ 152 - 76x = 120
12x-76x = 120-152
-64x = -32
x = -32/-64 = 1/2 (30 minutes)
As a result
y = 1-1/2 = 3/2 (1 hour, 30 minutes)
She ran for 30 minutes and use the jetpack for 1 hour and 30 minutes.
I think a is (8,-8)
B) (0,8)
First think out the equation, once you've done that multiply 3 by 25 to get 75
a) The total monthly cost is the sum of the fixed cost and the variable cost. If q represents the number of cones sold in a month, the monthly cost c(q) is given by
c(q) = 300 + 0.25q
b) If q cones are sold for $1.25 each, the revenue is given by
r(q) = 1.25q
c) Profit is the difference between revenue and cost.
p(q) = r(q) - c(q)
p(q) = 1.00q - 300 . . . . . . slope-intercept form
d) The equation in part (c) is already in slope-intercept form.
q - p = 300 . . . . . . . . . . . . standard form
The slope is the profit contribution from the sale of one cone ($1 per cone).
The intercept is the profit (loss) that results if no cones are sold.
e) With a suitable graphing program either form of the equation can be graphed simply by entering it into the program.
Slope-intercept form. Plot the intercept (-300) and draw a line with the appropriate slope (1).
Standard form. It is convenient to actually or virtually convert the equation to intercept form and draw a line through the points (0, -300) and (300, 0) where q is on the horizontal axis.
f) Of the three equations created, we presume the one of interest is the profit equation. Its domain is all non-negative values of q. Its range is all values of p that are -300 or more.
g) The x-intercept identified in part (e) is (300, 0). You need to sell 300 cones to break even.
h) Profit numbers are
425 cones: $125 profit
550 cones: $250 profit
700 cones: $400 profit
