getting

Type error

$--->81$ cost$\_$per$\_$route $=$ revenue$\_$per$\_$route.apply$($lambda x: calculate$\_$route$\_$cost$(($x$[\text{'}$ORIGIN$\text{'}],$ x$[\text{'}$DESTINATION$\text{'}])),$ axis$=1)$

$$

File $/$Library$/$Frameworks$/$Python$.$framework$/$Versions$/3\mathrm{.}13/$lib$/$python$3\mathrm{.}13/$site$-$packages$/$pandas$/$core$/$apply$.$py:$916,$ in FrameApply.apply$($self$)$

$...$

$51$ def $\_$sum$($a$,$ axis$=$None, dtype$=$None, out$=$None, keepdims$=$False,

$52$ initial$=\_$NoValue, where$=$True$)$:

$--->53$return umr$\_$sum$($a$,$ axis, dtype, out, keepdims, initial, where$)$

$$

TypeError: unsupported operand type$($s$)$ for $+$: 'float' and $\text{'}$str$\text{'}$