Sagot :
[tex]a- all\\
j-jazz\\
r_a-rap\\
r_c-rock\\\\
a=j+r_a+r_c\Rightarrow r_c=a-j-r_a\\\\
r_c=1-\frac{3}{8}-\frac{1}{4}\\\\
r_c=1-\frac{3}{8}-\frac{2}{8}\\\\
r_c=\frac{8}{8}-\frac{3}{8}-\frac{2}{8}\\\\
r_c=\frac{3}{8}[/tex]
rap - 1/4
jazz - 3/8
rock - x
all - 1
jazz + rap + rock = all
3/8 + 1/4 + x = 1
3/8 + 2/8 + x = 1
5/8 + x = 1
x = 1 - 5/8
x = 3/8
answer: rock - 3/8
jazz - 3/8
rock - x
all - 1
jazz + rap + rock = all
3/8 + 1/4 + x = 1
3/8 + 2/8 + x = 1
5/8 + x = 1
x = 1 - 5/8
x = 3/8
answer: rock - 3/8