Example : 30-12=18 thirty take away twelve is eighteen. 23-13=? 28-20=? 25-11=? 29-9=? 27-13=? 24-15=? 22-12=? 21-10=? 26-23 =?

23-13=10  Twenty-three take away thirteen is ten.
28-20=8  Twenty-eight take away twenty is eight.
25-11=14  Twenty-five take away eleven is fourteen.
29-9=20  Twenty-nine take away nine is twenty.
27-13=14  Twenty-seven take away thirteen is fourteen.
24-15=9  Twenty-four take away fifteen is nine.
22-12=10  Twenty-two take away twelve is ten.
21-10=11  Twenty-one take away ten is eleven.
26-23=3  Twenty-six take away twenty-three is three.