81*7/9=63 70*0,45=31,5 45:5/9=45*9:5=81 5х-10-х+1=9 4х=18 х=18:4 х=4,5
7/9 * 81 = 7 * 9 = 63 70 * (45/100) = 70 * 0.45 = 31.5 45 * 9/5 = 9 * 9 = 81 5x - 10 - x +1 = 9 4x - 9 = 9 4x = 9 + 9 4x = 18 x = 4.5