MikroTik

I am trying to make a script that greps the rx-bits-per-second: and tx-bits-per-second: of a interface and put in in a variable then send a sms something like below

:global tx
:global rx
/interface monitor-traffic ether1 once do={
:set tx $rx-bits-per-second
:set rx $rx-bits-per-second
/tool sms send usb2 phone-number=xxxxxxx message="$tx &rx" channel=1}

ok got it working by

interface monitor-traffic [/interface find name=ether1] once do={
:local tx (tx-bits-per-second / 1024);
:local rx (rx-bits-per-second / 1024);
:put $tx;
:put $rx;
/tool sms send usb2 phone-number=989xxxx message="tx = $tx rx = $rx" channel=1
}

can anyone point me in right direction on how can i add a variable to the sms