Answer
The friend is wrong
Work Step by Step
The temperature displayed in thermometer $A$ is $20^\circ$C and that in thermometer $B$ is $70^\circ$F.
To compare these two, we need to convert the temperatures into the same units.
The relation between two units is $$C = \frac{5}{9}(F - 32).\tag{1}$$ We use $F=70$ in equation $(1)$ to convert the temperature in thermometer $B$ in Celsius degrees: $$C = \frac{5}{9}(70 - 32)=\frac{5}{9}\cdot 38=\frac{190}{9}\approx 21.11^\circ \text{C}.$$ Since $21.11>20$, the temperature of thermometer $B$ is greater than that of $A$. Hence, the friend is wrong.
