Question

169+5×{32÷8+5×[40+8×(200÷a-72÷2)]}=1989

Answer 1

169+5*{32÷8+5*[40+8*(200÷a-36)]}=1989

5*{32÷8+5*[40+8*(200÷a-36)]}=1989-169=1820

32÷8+5*[40+8*(200÷a-36)]=1820:5=364

4+5*[40+8*(200÷a-36)]=364

5*[40+8*(200÷a-36)]=364-4=360

40+8*(200÷a-36)=360:5=72

8*(200÷a-36)=72-40=32

200÷a-36=32:8=4

200÷a=4+36=40

a=200:40=5

a=5