He will mix some 20% solution and some 70% solution to make 60% solution.
Let x = number of liters of 20% solution.
Let y = number of liters of 70% solution.
He wants to make 50 liters of 60% solution, so
x + y = 50 First Equation
The amount of acid in x amount of 20% solution is 20% of x, or 0.2x
The amount of acid in y amount of 70% solution is 70% of y, or 0.7y
The amount of acid in 50 liters of 60% solution is 60% of 50 liters, or 0.6 * 50 = 30
Now we add the amounts of acid.
0.2x + 0.7y = 30 Second Equation
x + y = 50
0.2x + 0.7y = 30
-0.2x - 0.2y = -10
0.2x + 0.7y = 30
------------------------
0.5y = 20
y = 40
x + y = 50
x + 40 = 50
x = 10
Answer: He needs 10 liters of 20% solution and 40 liters of 70% solution.
What you want to do here is take this information and plug it into point-slope form. any time you're given a point and a slope, you generally want to plug it into this equation: y - y1 = m(x - x1).
in this equation, m is your slope and (x1, y1) is a given point. plug in your info--slope of -3 and (-5, 2).
y - 2 = -3(x + 5)
that is the equation of your line. however, if you want to graph it, this doesn't really make much sense to you. convert it to slope-intercept form, y = mx + b, by solving for y.
y - 2 = -3(x + 5) ... distribute -3
y - 2 = -3x - 15 ... add 2
y = -3x - 13 is your equation.
to graph this, and any other y = mx + b equation, you want to start with your y-intercept if it's present. your y intercept here is -13, which means the line you wasn't to graph crosses the y-axis at y = -13, or (0, -13). put a point there.
after you've plotted that point, you use your slope to graph more. remember that your slope is "rise over run"--you rise up/go down however many units, you run left/right however many units. if your slope is -3, you want to go down 3 units, then go to the right 1 unit. remember that whole numbers have a 1 beneath them as a fraction. -3/1 is your rise over 1.
Answer:
D
Step-by-step explanation:
there isn't much of a harsh trend, but the graph shows that generally when the unemployment is lower, the life expectancy is higher, and when the unemployment is higher, the life expectancy is lower.
