As shown in the figure, two masses, $m_{1}=3.50 \mathrm{~kg}$ and $m_{2}=5.00 \mathrm{~kg}$. are on a frictionless tabletop and mass $m_{3}=7.60 \mathrm{~kg}$ is hanging from $m_{1}$. The coefficients of static and kinetic friction between $m_{1}$ and $m_{2}$ are 0.600 and $0.500,$ respectively.
a) What are the accelerations of $m_{1}$ and $m_{2}$ ?
b) What is the tension in the string between $m_{1}$ and $m_{3}$ ?