Jessie, Bella and Carrie go shopping. Jessie buys two apples and an orange which cost her $$40$$p. Bella buys one apple and two oranges, which cost her $$35$$p. Carrie buys one apple and one orange. How much does she pay? 
Overseas Competition->Knowledge Point->Word Problem Modules->Equation Word Problems->Multivariate Linear Equation Word Problems->Solving Problems by Solving System of 
Binary Linear Equations with Integer Coefficients 