I don't know the details. Wikipedia estimates Chinese losses as 26 000 killed, 37 000 wounded with 420 tanks and 66 guns lost. Vietnamese losses are estimated at 30 000 killed, 32 000 wounded, 185 tanks, 200 guns and 6 missile launchers lost - so it's safe to assume they didn't use butter knives.

Their preferred method of bombing might have been artillery, though - due to the lack of high capacity bomber aircraft, and due to lack of air superiority. Despite this, Wikipedia also mentions:

"The 372nd Air Division in central Vietnam as well as the 917th, 935th and 937th Air Regiments in southern Vietnam were quickly deployed to the north.[61]"

The Vietnamese source article is here. A relevant part seems to be this:

"When the border war began, the Ministry of National Defense also decided to send part of the 372nd Air Division (Hai Van Group) to the North to perform missions. From February 18 to March 3, 1979, squadrons of the 917th Air Regiment (Dong Thap Group), 935 (Dong Nai Group) and 937 (Hau Giang Group) including 10 UH-1 helicopters, 3 U-17 reconnaissance aircraft, 10 A-37 attack aircraft, and 10 F-5 fighter-bombers were deployed at Hoa Lac, Kep, Bach Mai and Noi Bai bases, respectively."

I'm unable to find more details.