212 + ( 48 - 2x ) : 40 - 3 = 3
212 +(48-2x):40 =3+3=6
=>212 + (48-2x) =6.40=240
=>(48-2x) =240-212 =28
48-2x=28
=>2x = 48-28 =20
=>x =20:2
=>x=10
\(212+\left(48-2.X\right):40-3=3\)\(=>212+\left(48-2.X\right):40=3+3\)
\(=>212+\left(48-2.X\right):40=6\)\(=>\left(48-2.X\right):40=6-212\)
\(=>\left(48-2.X\right):40=-206=>48-2.X=-206.40\)
\(=>48-2.X=-8240=>2.X=48--8240\)
\(=>2.X=8288=>X=8288:2\)
\(=>X=4144\)