an operational analysts has gathered the following data on a fridge repairs:

$1.$ design capacity of the shop is $120$ fridges

$2.$ Effective capacity is shop is $80$ fridges

$3.$ Backlog in the system is $20$ fridges

$4.$ The actual service rate is $67$ for past month

$5.$ expected capacity was $90$ fridges

$6.$ capacity in the system is $30$ fridges

whats the effective utilization of the fridge repair shop?