The number of boys in a tennis club is 10 more than half the number of girls. If there are 40 boys in the tennis club, find the total number of boys and girls in the club.

So the number of boys = $\frac{x}{2}+10$

So we have;

$\frac{x}{2}+10=40\phantom{\rule{0ex}{0ex}}\Rightarrow \frac{x}{2}=40-10\phantom{\rule{0ex}{0ex}}\Rightarrow \frac{x}{2}=30\phantom{\rule{0ex}{0ex}}\Rightarrow x=30\times 2=60$

Therefore the number of girls = 60

And total number of boys and girls = 60 + 40 = 100

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