0,4(a-4)-0,3(a-3)=1,7
0,4a-1,6-0,3a+0,9=1,7
0,1a=1,7+0,7
0,1a=2,4
a=24
Ответ:24
Х - нужно вложить
х*0,12=54
х= 54/0,12= 450 грн
4x - 2(3 + x) = 9 - x
9 - x = 4x - 2(3 + x)
9 = x + [4x - 2(3 + x)]
9 = x + [4x - (2 · 3 + 2x)
9 = x + [4x - (6 + 2x)
9 = x + [4x - 2x - 6]
9 = x + [2x - 6]
9 = x + 2x - 6
9 = 3x - 6
3x = 9 + 6
3x = 15
x = 15 ÷ 3
x = 5