Question

Aflați numărul natural a pentru care avem 2 x {120-2x [(12+a)÷15+108]÷11}=200

Answer 1

120-2•[(12+a):15+108]:11=100
2•[(12+a):15+108]:11=20
2•[(12+a):15+108]=220
(12+a):15+108=110
(12+a):15=2
12+a=30
a=18

Answer 2

2 x {120-2x [(12+a)÷15+108]÷11}=200 {120-2x [(12+a)÷15+108]÷11}=200 : 2
120-2x [(12+a)÷15+108]÷11=100
2x [(12+a)÷15+108]÷11 = 120-100
2x [(12+a)÷15+108]÷11 = 20
2x [(12+a)÷15+108] = 20×11
2x [(12+a)÷15+108] = 220
(12+a)÷15+108 = 220:2
(12+a)÷15+108 = 110
(12+a)÷15 = 110 - 108
(12+a):15 = 2
12+a = 2 × 15
12+a = 30
a = 30-12
a = 18