\( \begin{array}{ll}\text { 20. } & (-3)+7= \\ \text { 21. } & (-4)+14= \\ \text { 22. } & (-1)-5= \\ \text { 23. } & (-1)+(-4)= \\ \text { 24. } & (-12)+(-2)= \\ \text { 25. } & 0-(-6)= \\ \text { 26. } & 2-(-5)=\end{array} \)

Si el ratio de alumnos a maestras es 4:1 y hay 12 alumnos, ¿cuántas maestras hay?

Mr nixon and his son went fishing Mr nixon caught a snapper that weighed \( 21 / 2 \) pounds His son caught a snapper that weighed \( 1 / 4 \) Calculate the total weight of the fieh caught.

2. In Buffalo, New York, the temperature was \( { }^{-1} 4^{\circ} \mathrm{F} \) in the morning. If the temperature dropped \( 7^{\circ} \mathrm{F} \), what is the temperature now?

A store sells 2.75 liters of juice in one bottle and 1.25 liters in another. How many liters of juice do you have altogether?

Soit \( \left(v_{n}\right) \) la suite définie par \( v_{0}=2,1 \) et, pour tout entier \( n \geq 0 \), par \( v_{n+1}=v_{n}+0,4 \). \( \left(v_{n}\right) \) est une suite arithmétique de raison 0,4 et de premier terme \( v_{0}=2,1 \). Pour tout entier \( n \geq 0, v_{n}=0,4 n+2,1 \). Calculer le terme \( v_{24} \) (on donnera la valeur exacte). \( v_{24}= \). 4.