Answer:
Step-by-step explanation:
c(f) = [tex]\frac{5}{9}(f-32)[/tex]
[tex]-21 = \frac{5}{9}(f-32)[/tex]
Multiply both sides by 9
-21*9 = 5(f - 32)
-189 = 5*f - 5*32
-189 = 5f - 160
Add 160 to both sides
-189 + 160 = 5f
-29 = 5f
Divide both sides by 5
-29/5 = f
f = -5.8
f = -6 °C
