1.5x=6.6
2x+6=21
28.7÷14=
2.52÷3.5=
☆7.28÷1.3=
a×12=
b×b=
a×b=
x×y×7=
5×x=
2×c×c=
7x×5=
2×a×b=
a·a=
6×m×7n=
8a×9b×10c=
a×a×a=
28.7-14.7+1.4
21÷3.5+21÷1.5
56.14÷3.5÷2
6.17×13.6+1.36×( )(填数使它可简便计算)
4.2x-2.6x=4.88
5(20x+1.5)=17.5