10/24+ 11/12 + 20/48 = 20/48 + 44/48 + 20/48 = 84/48 = 7/4 = 1,75
5 * 1,75x = 480
1,75x = 480 : 5
1,75x = 96
x = 96 : ( 3/4 )
x = 128
Ответ 128
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1)8x-15,3=6x-3,3
8x-6x=-3,3+15,3
2x=12
x=6
2)18-(6x+5)=4-7x
18-6x-5=4-7x
-6x+7x=4-18+5
x=-9
3)6(x+0,5)-3=9
6x+3-3=9
6x=9
x=1,5