The simple interest S is given by
[tex]S=\frac{P\cdot r\cdot t}{100}[/tex]where P is the principal, t the time (years) and r is the interest rate.
In our case, P=700, r=0.18, and t=6. By substituting these values, we have
[tex]\begin{gathered} S=\frac{700\cdot0.18\cdot6}{100} \\ S=\frac{756}{100} \\ \\ \end{gathered}[/tex]then, the interest S is equal to $7.56, which corresponds to option A