S14 I can subtract HTU - HTU with exchanging.

S15 I can subtract and p.



S16 I can subtract ThHTU HTU.

S17 I can subtract U.t U.t.



S18 I can subtract numbers with different amounts of digits.

S19 I can subtract U.th U.th.



S20 I can subtract whole numbers and decimals.

S21 I can subtract negative numbers in a context (e.g. temperature).