35+48 = 51-7 = 59+31 = 72-27 =
9×6+8 = 4×8-9 = 5×7+35 = 6×8-30=
5×4= 8×7= 9×4= 68-6=
9×8= 39+6= 70-5= 4×6=
7+5×5= 8×7-20= 27+(12-5)= 8×8+14=
足球上黑色皮共有12块,白色皮比黑色皮的2倍少4块,白色皮共有多少块?