Jawabanmu

2014-09-11T22:38:10+07:00
1. (13a-8b) + (12a+9b)
    = 13a-8b+12a+9b
    = 13a+12a-8b+9b
    = 25a+b
2. (15i+14b+13k) + (-30i-45j+51k)
    = 15i+14b+13k-30i-45j+51k
    = 15i-30i+14b+13k+51k-45j
    = -15i+14b+64k-45j
3. (3-17x+35z) + (4x+23y-9)
    = 3-17x+35z+4x+23y-9
    = -17x+4x+35z+23y+3-9
    = -13x+35z+23y-6
4. (42n+35m+7) - (50m-20n+9)
    = 42n+35m+7-50m+20n-9
    = 42n+20n+35m-50m+7-9
    = 62n-15m-2

coba diteliti lagi ya
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