Question

the temperature rises by 18 degree Fahrenheit. what is the rise on celcius scale ? and the answer is 10

Answer 1

F = 32 + 180/100 * C
F1 - F2 = 1.8 * (C1 - C2)
So 18 = 1.8 * (C1 - C2)
Answer = 10 deg C.

Answer 2

 we know,
   180 division of fahenheit scale = 100 divison of Celcius scale 
    e.g if 180 change in F scale = 100 change in C scale 
   hence ,
      ΔF × 100 = ΔC × 180
   A/C to question,
     ΔF = 18°
18 × 100 = ΔC × 180
ΔC = 10°