\(a,\left(2\times x-40\right):10=-55\)
\(2\times x-40=-55\times10\)
\(2\times x-40=-550\)
\(2\times x=-550+40\)
\(2\times x=-510\)
\(x=-510:2\)
\(\Rightarrow x=-255\)
\(b,\left(2\times x+15\right):5=-40\)
\(2\times x+15=-40\times5\)
\(2\times x+15=-200\)
\(2\times x=-200-15\)
\(2\times x=-215\)
\(x=-215:2\)
\(\Rightarrow x=-\dfrac{215}{2}\)
\(c,\left(2\times x-72\right):8=25\)
\(2\times x-72=25\times8\)
\(2\times x-72=200\)
\(2\times x=200+72\)
\(2\times x=272\)
\(x=272:2\)
\(\Rightarrow x=136\)
a. ( 2.x - 40 ) ÷ 10 = -55
2.x - 40 = (-55) × 10
2.x - 40 = -550
2.x = (-550) + 40
2.x = -510
x = (-510) ÷ 2
x = -255
b. ( 2.x + 15 ) ÷ 5 = -40
2.x + 15 = (-40) × 5
2.x + 15 = -200
2.x = (-200 ) - 15
2.x = -215
x = (-215) ÷ 2
x = -107,5
c. ( 2.x - 72 ) ÷ 8 = 25
2.x - 72 = 25 × 8
2.x - 72 = 200
2.x = 200 + 72
2.x = 272
x = 272 ÷ 2
x = 136
