<em>x</em>/<em>r</em> + <em>x</em>/<em>w</em> + <em>x</em>/<em>t</em> = 1
<em>x</em> (1/<em>r</em> + 1/<em>w</em> + 1/<em>t</em>) = 1
<em>x</em> = 1 / (1/<em>r</em> + 1/<em>w</em> + 1/<em>t</em>)
To make the solution a bit cleaner, multiply through the numerator and denominator by the LCM of each fraction's denominator, <em>rwt</em> :
<em>x</em> = 1 / (1/<em>r</em> + 1/<em>w</em> + 1/<em>t</em>) • <em>rwt</em> / <em>rwt</em>
<em>x</em> = <em>rwt</em> / (<em>rwt</em>/<em>r</em> + <em>rwt</em>/<em>w</em> + <em>rwt</em>/<em>t</em>)
<em>x</em> = <em>rwt</em> / (<em>wt</em> + <em>rt</em> + <em>rw</em>)
3/20 is 0.15....
If you do 3 divided by 20 it equals 0.15
Choice A is true. This is the Pythagorean identity. One of the most fundamental trig identities you should memorize.
Choice B is false. Let A = 60 and B = 30 and you'll see the left hand side turn into 0.5 while the right hand side turn into -0.5
Choice C is true. This is a variation of the identity tan^2+1 = sec^2 (just subtract tan^2 from both sides)
Choice D is true as this is a more complicated variation of 1+tan^2 = sec^2
Answer: 11 yards
Step by step: multiple 7 by 2 because you lost 7 yards in 2 days. You would get 14 yards back from the starting line of scrimmage, but you still need to add the 3 yards they gained leaving you with 11.
