计算:(1)208×145﹣24990÷238(2)10﹣1×3﹣1÷1(3)(2.76÷0.3﹣4)×(0.25+)(4)[3﹣(0.2+)×4.5]÷2(5)(15.4﹣6×)÷(2+)
计算 1.25﹣(+)×80%
计算:6×﹣5×.
解方程: 2+1.8﹣5ⅹ=3.6 2ⅹ÷2.3=4.5 0.2(5x﹣1)+5(x﹣1)="0.8" 7(ⅹ﹣1.2)=2.1.
简算 4.9+0.1﹣4.9+0.1 10.78﹣(2.78+3.693) 99.99×22.22+33.33×33.34 (2.5×2.5+2.5×2.5+2.5×2.5+2.5×2.5)×8.
计算