notice, the graph starts off with an account balance of $10, at the 10 over the y-axis, that means the initial amount in the account, or what he initially deposited was 10 bucks.
now... let's use any of the points, say hmm the 2, 10.44.
after 2 years, he's got an extra 44 cents in it, went up to 10.44.
bearing in mind that is a linear graph, and thus is a simple interest rate.
[tex]\bf \qquad \textit{Simple Interest Earned Amount}\\\\
A=P(1+rt)\qquad
\begin{cases}
A=\textit{accumulated amount}\to &10.44\\
P=\textit{original amount deposited}\to& \$10\\
r=rate\to r\%\to \frac{r}{100}\\
t=years\to &2
\end{cases}
\\\\\\
10.44=10(1+r2)\implies \cfrac{10.44}{10}=1+2r\implies 1.044=1+2r
\\\\\\
1.044-1=2r\implies \cfrac{0.044}{2}=r\implies 0.022=r
\\\\\\
0.022=\cfrac{r}{100}\implies 0.022\cdot 100=r\implies \stackrel{\%}{2.2}=r[/tex]
