[tex] \frac{7}{9} [/tex] от 81
45% от 70
число, [tex] \frac{5}{9} [/tex] которого равны 45
[tex]5(x - 2) - (x - 1) = 9[/tex]

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

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