#### Answer

$\frac{2+x}{5+5}=\frac{5}{10} $
$\frac{2+x}{10}=\frac{5}{10}$
$2+x=5$
$x=5-2$
$x=3$

#### Work Step by Step

When solving an equation to answer Qn 3, we have to ensure that the total number of shots made divided by (the total number of shots made + the total number of shots missed) is 50%, or $\frac{5}{10}$.
Hence, we use the following equation:
$\frac{2+x}{5+5}=\frac{5}{10} $
$\frac{2+x}{10}=\frac{5}{10}$
$2+x=5$
$x=5-2$
$x=3$
We cannot try to solve using an equation to get an 80% shooting success rate if we shoot 5 more shots since we have to make 8 out of 10 shots to have an 80% shooting success rate within 10 shots, and we already missed 3 shots during the first 5 shots so the best we can get is a 70% shooting success rate if we make all 5 of the next shots.