68................ i think so
First, let's see what we are told:
1. The ratio of boys to girls is 3:2. Turn that into an equation
<span><span>2b=3g</span><span>2b=3g</span></span>
2. If two girls are added, the number will be equal
<span><span>b=g+2</span><span>b=g+2</span></span>
Now, substitute the second equation into the first:
<span><span>2(g+2)=3g</span><span>2(g+2)=3g</span></span>
multiply
<span><span>2g+4=3g</span><span>2g+4=3g</span></span>
subtract 2g
<span><span>4=g</span><span>4=g</span></span>
<span>So there are 4 girls and, thus 6 boys</span>
<span>cos<span>[<span><span>7pi/</span>4</span>]</span></span>=<span>cos<span>(2pi−pi<span>4</span>)
</span></span> =<span>cos<span>(−pi/<span>4</span>)
</span></span> =<span>cos<span>(pi<span>4</span>)
</span></span> =<span><span><span>√2/</span>2</span></span>