Respuesta :

jackattackblunt
because α varies directley to β
[tex] \alpha = k \beta [/tex]
(k = constant)

α=7 when β=2
7= 2k
k= [tex] \frac{7}{2} [/tex]

so when α=21
21= [tex] \frac{7}{2} [/tex] b
b= 6