P is partly constant and partly varies with q when p=530,q=1600 and when p=730,q=3600, find :

(i) The formula connecting p and q
(ii) r when e=1300

P = mq + c

when p = 530, q = 1600
1600m + c = 530
when p = 730, q = 3600
3600m + c = 730

subtract them
2000m = 200
m = 1/10
then in 3600m + c = 730
3600(1/10) + c = 730
c = 370

(i) p = (1/10)q + 370

(ii) r when e=1300 <----- no connection to our question, you figure it out