Question

Efectuati: {637+15.[15.(282:47+516:43):45-6]:21}:13=?

Answer 1

{637+15*[15*(6+12):45-6]:21}:13
{637+15*(15*18:45-6):21}:13
{637+15*0:21}:13
637:13
=49

Answer 2

= {637+15 * [15 * (6+12):45-6]:21}:13 
= [637+15 * (15 * 18:45-6):21]:13
= [637+15 * (270:45-6):21]:13
= [637+15 * (6-6) :21]:13
= [637+15 * 0:21]:13
= 637:13 
= 49