[tex]a) {2}^{5x - 4} = {2}^{11} [/tex]
[tex]5x - 4 = 11[/tex]
[tex]5x = 11 + 4[/tex]
[tex]5x = 15 \: | \div 5[/tex]
[tex]x = 3[/tex]
[tex]b) {7}^{3x + 5} = {7}^{x + 9} [/tex]
[tex]3x + 5 = x + 9[/tex]
[tex]3x - x = 9 - 5[/tex]
[tex]2x = 4 \: | \div 2[/tex]
[tex]x = 2[/tex]
