4a-a=3.06解：3a=3.06a=3.06÷3a=1.02
4a-a=3.063a=3.06a=1.02
4a-a=3a，即3a=3.06a=3.06/3=1.02
3a等于3.06a等于3.06a÷3a等于2.06
