Explicație pas cu pas:
[tex] \bf 120+5 \cdot\big[28-3 \big(2x-20 \big) \big]=140[/tex]
[tex]\bf 5 \cdot\big[28-3 \big(2x-20 \big) \big]=140 - 120[/tex]
[tex]\bf 5 \cdot\big[28-3 \big(2x-20 \big) \big]=20 \: \: \: \: \: \bigg| : 5[/tex]
[tex]\bf 28-3 \cdot \big(2x-20 \big)=4[/tex]
[tex]\bf 28 = 4 + 3 \cdot \big(2x-20 \big)[/tex]
[tex]\bf 28 - 4 = 3 \cdot \big(2x-20 \big)[/tex]
[tex]\bf 24 = 3 \cdot \big(2x-20 \big) \: \: \: \:\bigg| :3[/tex]
[tex]\bf 8= 2x-20 [/tex]
[tex]\bf 8 + 20 =2x[/tex]
[tex]\bf 28 =2x \:\: \: \: \bigg| :2 [/tex]
[tex]\bf 14 =x [/tex]
[tex] \red{ \underline{ \: \bf x = 14 \: }}[/tex]
