Answer:
x = [tex]\frac{a(k-r)}{7}[/tex]
Step-by-step explanation:
Given
a = [tex]\frac{7x}{k-r}[/tex] ( multiply both sides by (k - r) )
a(k - r) = 7x ( divide both sides by 7 )
[tex]\frac{a(k-r)}{7}[/tex] = x
