## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$C(t)= 30t+90$, $7$ months
Let $t$ = months of membeship. Then $C(t)= 30t+90$ and the t for which $C(t)=300$ is found from $300= 30t+90\qquad$ ... subtract 90 $210=30t\qquad$ ... divide with 30 $t=7$ months