15-6= 37-30= 42+8= 6+28=
30+34= 48-4= 60+20= 72+20=
27+9= 5+15= 54-40= 55-5=
100-10= 26-8= 70-9= 43+4=
3+48-20= 67-60-7= 18+9+6= 35-6+8=