Question

412÷4-{12-2×[36-4×(9÷x)]+5×12}÷6=91

Answer 1

412:4-{12-2×[36-4×(9:x)]+5×12}:6=91
103-{12-2×[36-4×(9:x)]+60}:6=91
{12-2×[36-4×(9:x)]+60}:6=103-91
{12-2×[36-4×(9:x)]+60}:6=12
12-2×[36-4×(9:x)]+60=12×6
12-2×[36-4×(9:x)]+60=72
12-2×[36-4×(9:x)]=70-60
12-2×[36-4×(9:x)]=10
2×[36-4×(9:x)]=12-10
2×[36-4×(9:x)]=2
36-4×(9:x)=2:2

36-4×(9:x)=1
4×(9:x)=36-1
4×9:x=3536:x=35

x=35:36
x=0,97(2)