Hi Ski,

this question can be solved using the model I drew here : https://ibb.co/jHADuG

L = Linda’s marks, B = …, etc.

Linda, Kathy, Bob and Peter scored an average of 77 marks in a Math test -> ( L + K + B + P ) / 4 = 77

Peter’s score was 60% of Linda’s score -> P = L * (60/100) = 0.6L

Bob got 5 more marks than Linda -> B = L + 5

Kathy scored 21 marks less than Linda -> K = L – 21

The above 3 means:

( L + K + B + P ) / 4 = 77 -> ( L + L – 21 + L + 5 + 0.6L )/4 = 77 -> ( 3.6L – 16 ) = 308 -> L = 90

K + P = L -21 + 0.6L = 1.6L -21 = 1.6*90 – 21 = **123**

If this answer helped, please like and accept it so we can help others 🙂 !

-Michelle (www.dingletutors.com)