Question

Sub 25
Ques. 6

David paid $9.50 for some 15 cent, 25 cent, and 45 cent stamps. He bought 38 stamps and the number of 25 cent stamps was 8 more than twice the number of 45 cent stamps. How many of each type did David buy?

Answer 1

$$\left\{ \begin{array}{l} 15x + 25y + 45z = 950 \\ x + y + z = 38 \\ y = 2z + 8 \end{array} \right.$$ $$\left\{ \begin{array}{c} y = 2z + 8 \\ x = 30 - 3z \\ 450 - 45z + 50z + 200 + 45z = 950 \end{array} \right.$$ $$\left\{ \begin{array}{l} z = 6 \\ y = 20 \\ x = 12 \end{array} \right.$$