Hello Mark,
cool question actually and yes it works.
Let's create a demo-dataset first:
library(tidyverse)
dataframe = tibble(ID = LETTERS[1:9],
value = c("72+3", "58+3", "43",
"87+3", "74+3", "65",
"86+5", "86+3", "70+1"))
Then you can convert the values into something taht is called expression, and this can then be evaluated, in other words the calculation is performed.
new_dataframe = dataframe %>%
rowwise() %>%
mutate(new_value = eval(parse(text = value)))
Here a new dataframe is created and in that a new column ("new_value") you can also overwrite the existing column by inserting this line in the code above:
mutate(value = eval(parse(text = value)))
Matthias