Answer:
Cost of 1 CD = x = £3
Cost of 1 DVD = y = £7
Step-by-step explanation:
Let us represent:
Cost of 1 CD = x
Cost of 1 DVD = y
i. Form a pair of simultaneous equations to represent these two sentences
2 CDs and 9 DVDs cost £69.
2x + 9y = 69.... Equation 1
2 CDs and 6 DVDs cost £48.
2x + 6y = 48..... Equation 2
ii. Solve the simultaneous equations to find the cost of 1 CD and 1 DVD.
Combining both equations together:
2x + 9y = 69.... Equation 1
2x + 6y = 48..... Equation 2
We substract Equation 2 from Equation 1
3y = 21
y = £7
Solving for x using Equation 1
2x + 9y = 69.... Equation 1
2x + 9 × 7 = 69
2x + 63 = 69
Collect like terms
2x = 69 - 63
2x = 6
x = 6/2
x = £3
Therefore,
Cost of 1 CD = x = £3
Cost of 1 DVD = y = £7
