This is an easy question on application of algebra.

First, you should write down all the facts you know.

(P for Phil, L for Lia and C for Cam.)

P + L + C = 200.30

P = L + 12.80

C = 3L

Second, you should find common letter in those equations.

In this case, it's L.

So, you should subtitute P = L + 12.80 and C = 3L to P + L + C= 200.30.

Then you will get (L + 12.80) + L + 3L = 200.30

Third, then you can solve it using basic algebra.

(L + 12.80) + L + 3L = 200.30

= 5L + 12.80 = 200.30

= 5L = 187.50

= L = 37.5

Lia collected 37.5.

Fourth, You just subtitute L to other equations.

Then you will get C and P as well.

Hope it helped!