15(x-3)+12(x+1)-25(x-3)=-92 ausmultiplizieren
15 * x - 45 + 12 * x + 12 - 25 * x + 75 = -92
15 * x + 12 * x - 25 * x = - 92 + 45 - 12 - 75
2 * x = -134
x = - 67
Probe
15 * ( -67 - 3 ) + 12 * ( -67 + 1 ) - 25 * ( -67 - 3 ) = - 92
- 1050 - 792+ 1750 = -92
-92 = -92
mfg Georg