Answer: it cost a customer $7.25 to buy five tulips and $10.5 to buy six roses.
Step-by-step explanation:
Let x represent the cost of 1 tulip.
Let y represent the cost of 1 rose.
The price of each tulip is the same and the price of each roses the same. One customer bought seven tulips and nine roses for $25.90. This means that
7x + 9y = 25.9 - - - - - - - - - - - - - - 1
Another customer bought for four tulips and eight roses for $19.80. This means that
4x + 8y = 19.8- - - - - - - - - - - - - - - 2
Multiplying equation 1 by 4 and equation 2 by 7, it becomes
28x + 36y = 103.6
28x + 56y = 138.6
Subtracting, it becomes
- 20y = - 35
y = - 35/ - 20
y = 1.75
Substituting y = 1.75 into equation 2, it becomes
4x + 8 × 1.75 = 19.8
4x + 14 = 19.8
4x = 19.8 - 14 = 5.8
x = 5.8/4
x = 1.45
The cost of 5 tulips would be
1.45 × 5 = $7.25
The cost of 6 roses would be
1.75 × 6 = $10.5
