Resposta :
d) 20
[tex]\sf4x - 5y = 50 \\4x - 5 * 6 = 50 \\4x - 30 = 50 \\4x = 30 + 50 \\4x = 80 \\x = 80/4 \\\boxed{\sf x = 20}[/tex]
d) 20
[tex]\sf4x - 5y = 50 \\4x - 5 * 6 = 50 \\4x - 30 = 50 \\4x = 30 + 50 \\4x = 80 \\x = 80/4 \\\boxed{\sf x = 20}[/tex]