Question

[2+b x( 40-4 x 5) + 13] x 10 = 550

Answer 1

[2+b×(40-4×5)+13]×10=550
[2+b×(40-20)+13]×10=550
(2+b×20+13)×10=550
(2+20b+13)×10=550
2+20b+13=550:10
2+20b+13=55
2+20b=55-13
2+20b=42
20b=42-2
20b=40
b=40:2
b=20

Answer 2

[2+b×(40-20)+13]=550:10
 2+b×20+13=55
15+b×20=55
b×20=55-15
b×20=40
b=40:20
b=2