X liters of 10% + (30 - x) liters of 22% = 30 liters of 15%

Plugging in the numbers 
x(10) + (30 - x)22 = 30(15) 

Distribute 
10x + 660 - 22x = 450 

Combine like terms 
-12x = -210 

Divide both sides by -12 
x = 17.5 
30 - x = 12.5 

17.5 liters of 10% + 12.5 liters of 22% = 30 liters of 15%

THE TRICK IS TO JUST USE ONLY ONE VARIABLE

4 0

2 years ago

two trains leave towns 480 km apart at the same time and travel toward each other. one train travels 18 km/h faster than the oth

KonstantinChe [14]

$\begin{gathered} \text{Let assume one train spe}ed\text{ is x km/h} \\ \text{Second train spe}ed\text{ is }\Rightarrow(x+18)\text{ km/h} \\ \text{They m}eet\text{ in 2 hour,so} \\ 2=\frac{480}{x+x+18} \\ 2x+18=\frac{480}{2} \\ 2x=240-18 \\ x=\frac{222}{2} \\ x=111\text{ km/h (1st train spe}ed) \\ x+18=111+18=129\text{ km/hr (2nd rain sp}eed)\text{ } \end{gathered}$

3 0

11 months ago

If f(x) = (3x + 8)/(2x - A) and f(0) = -2, what is the value of A?

Mrac [35]

Using the given info, we can determine that
$(3(0) + 8) \div (2(0) - a) = - 2$
simplify
$8 \div - a = - 2$
multiply both sides by -a
and divide each side by -2
$4 = a$
A = 4

5 0

2 years ago