<span>63:21 = 3
72:18 =</span><span> 4</span>
<span>92:23 = 4</span>
<span>98:14 = </span>7
<span>74:37 = 2</span>
9(3a-7b+8c)
e(a-b+c)=e×a-e×b+e×c
27a-63b+72c
...........................
<span>42*7+5*42/84*6-4*84=42*(7+5)/84*(6-4)=12/2*2=6/2=3</span>