Sulian runs a moving company. Her production function for moving services is

$(1,2)=4012+1+2$

f

$($

x

$1$

$,$

x

$2$

$)$

$=$

$40$

x

$1$

x

$2$

$+$

x

$1$

$+$

x

$2$

where $1$

x

$1$

is the amount of labour and $2$

x

$2$

is the number of trucks she needs.