lili0301

Verified answer

3x+7x+18=178
10x+18=178
10x=178-18
10x=160
x=160/10
x=16
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6y-2y+25=65
4y+25=65
4y=65-25
4y=40
y=40/4
y=10
____________________________
7z+6z-13=130
13z-13=130
13z=130+13
13z=143
z=143/13
z=11
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21t-4t-17=17
17t-17=17
17t=17+17
17t=34
t=34/17
t=2