[latex]2 ^{x} +2 ^{x+2} =40[/latex]

[latex]2 ^{x} +2 ^{x+2} =40 2 ^{x} +2 ^{2} *2 ^{x}=40 2 ^{x} +4*2 ^{x} =40 5*2 ^{x} =40 |:5 2 ^{x} =8 2 ^{x}=2^{3} x=3[/latex]