Question

Note: The direction of the acceleration ~a of
the system is given in the figure.
Three masses (17 kg, 21 kg and 67 kg) are
connected by strings. The 67 kg mass slides
on a horizontal surface of a table top and the
17 kg and 21 kg masses hang over the edge of
the surface. The string connecting the 17 kg
and 67 kg masses runs over a massless and
frictionless pulley. The coefficient of sliding
friction, µ, between the 67 kg mass and the
table top is 0.384.
The acceleration of gravity is 9.8 m/s.

Find the magnitude of acceleration of the system.
Answer in units of m/s
2
.

plz help