Since the units are all the same, I'll drop them for the purposes of adding/subtracting the numbers together.
We work from left to right, which means we do this first:
color(white)(0)9.5
ul(17.286)
26.786
Now we can do the subtraction:
26.786
ul(color(white)(0)1.4445)
See that the 26.786 doesn't have enough digits, and so we put in 0 as a place holder:
26.7860
ul(color(white)(0)1.4445)
We start from the right and move left. First we have 0-5 which doesn't work, and so we borrow from the 6 next to the 0. The 6 is reduces by 1 to 5 (we've borrowed 1) but because we're getting it from the next place up, it's worth 10 to the next place down:
26.78cancel(6)^5cancel(0)^10
ul(color(white)(0)1.444color(white)(0)5)
10-5=5:
26.78cancel(6)^5cancel(0)^10
ul(color(white)(0)1.444color(white)(0)5)
color(white)(0000000)5
And we can do the rest of the subtractions:
26.78cancel(6)^5cancel(0)^10
ul(color(white)(0)1.444color(white)(0)5)
25.341color(white)(0)5
Giving 25.3415mm
