Is there a trick to finding the value of X?
Example:
75% of x = 1050
90% of x = 1260
I know that x = 1400, but I'm wondering if there's an easy way to find it out quickly.
Thx!
of = "Multiply" $\displaystyle 75 \%=\frac{3}{4} \mbox{ and }90 \%=\frac{9}{10}$
so solving each equation gives.
$\displaystyle \frac{3}{4}x=1050 \iff x=\frac{4}{3}1050=4 \cdot 350=1400$
and the second
$\displaystyle \frac{9}{10}x=1260 \iff x =\frac{10}{9}1260=10 \cdot 140=1400$
Fractions can make calculations alot easier.
I hope this helps.
actually, i'm confused (again) at this part:
$\displaystyle
x=\frac{4}{3}1050=4 \cdot 350=1400
$
how does this give us 4? and why is the 4 and 3 flipped? division?
$\displaystyle
x=\frac{4}{3}1050=4
$
also, where does this come from?
$\displaystyle
4 \cdot 350
$
yeah, so where does the the 350 and 140 come from? how is it derived?
$\displaystyle \frac{3}{4}x=1050$ so we divide both sides by 3/4
$\displaystyle \frac{\frac{3}{4}x}{\frac{3}{4}}=\frac{1050}{\frac {3}{4}}$
remember that 1050 can be written as a fraction $\displaystyle \frac{1050}{1}$
and if we have a fraction divided by a fraction it is the same as multiplying by the reciprocial.
So now we get...
$\displaystyle x=\frac{\frac{1050}{1}}{\frac{3}{4}}=\underbrace{\ frac{1050}{1}\cdot \frac{4}{3}}_{1050/3=350}=350 \cdot 4=1400$
I hope this clears it up