Question

a indicação de uma temperatura na escala fahrenheit excede em 2 unidades o dobro da correspondente indicação em celsius. essa temperatura e:

Answer 1

celsius (C) -> x
fahrenheit (F) -> 2x+2

C = (F − 32) / 1,8
x  = (2x+2-32)/1,8
1,8x = 2x-30
-0,2x = -30
x = -30/-0,2 = 150ºC

Answer 2

$\tt 9tc\:=\:5\cdot \left(2tc\:-\:30\right)\\\\\\\tt 9tc=10ct-150\\\\\\\tt 9tc-10ct=10ct-150-10ct\\\\\\\tt -ct=-150\\\\\\\displaystyle \frac{-ct}{-t}=\frac{-150}{-t}\\\\\\\boxed{\tt C=150^\circ}$