Solution:
Given the arithmetic equation below
[tex]\begin{gathered} c=4+(n-1)\cdot3 \\ Where \\ n\text{ is the of friends \lparen term\rparen} \\ c\text{ is the number of cans of soda} \end{gathered}[/tex]
1) For term 6, i.e. n = 6,
Substitute 6 for n into the equation above
[tex]\begin{gathered} c=4+\left(6-1\right)\cdot \:3 \\ c=4+(5)(3)=4+15=19 \\ c=19 \end{gathered}[/tex]
Hence, answer is b (19 cans)
2) For term 4, i.e. n = 4,
Substitute 4 for n into the equation above
[tex]\begin{gathered} c=4+\left(4-1\right)\cdot \:3 \\ c=4+(3)(3=4+9=13 \\ c=13 \end{gathered}[/tex]
Hence, the answer is d (13 cans)
3) For term 2, i.e. n = 2,
Substitute 2 for n into the equation above
[tex]\begin{gathered} c=4+\left(2-1\right)\cdot \:3 \\ c=4+(1)(3)=4+3=7 \\ c=7 \end{gathered}[/tex]
Hence, the answer is a (7 cans)
4) For term 1, i.e. n = 1
Substitute 1 for n into the equation above
[tex]\begin{gathered} c=4+\left(1-1\right)\cdot \:3 \\ c=4+(0)(3)=4+0=4 \\ c=4 \end{gathered}[/tex]
Hence, the answer is c (4 cans)