a) 4.x - 15 = -75 - x
=> 4x + x = -75 + 15
=> 5x = -60
=> x = -60/5 = -12
b) 72 - 3.x = 5.x + 8
=> -3x - 5x = 8 - 72
=> -8x = -64
=> x = -64/-8 = 8
Bài giải
a, \(4\cdot x-15=-75-x\)
\(4x+x=-75+15\)
\(5x=-60\)
\(x=-60\text{ : }5\)
\(x=-12\)
b, \(72-3\cdot x=5\cdot x+8\)
\(5x+3x=72-8\)
\(8x=64\)
\(x=64\text{ : }8\)
\(x=8\)
a, \(4\cdot x-15=-75-x\)
\(4x+x=-75+15\)
\(5x=-60\)
\(x=-60\text{ : }5\)
\(x=-12\)
b, \(72-3\cdot x=5\cdot x+8\)
\(5x+3x=72-8\)
\(8x=64\)
\(x=64\text{ : }8\)
\(x=8\)