Resposta:

Explicação passo a passo:

[tex]1,50 + 1,50*x = 1,80\\\\1,50x = 1,80 - 1,50\\\\1,50x = 0,30\\\\x = \frac{0,30}{1,50} \\x = \frac{20}{100} \\\\[/tex]

x = 20%