Answer:
The cost of one rose bushes be $10 and the cost of shrubs $4.
Step-by-step explanation
Let us assume that the cost of rose bushes be x .
Let us assume that the cost of shrubs be y .
As given
Rob and Amy each improved their yards by planting rose bushes and shrubs.
They bought their supplies from the same store.
Rob spent $100 on 8 rose bushes and 5 shrubs.
Than the equation
8x + 5y = 100
Amy spent $112 on 8 rose bushes and 8 shrubs.
8x + 8y = 112
Than the two equation
8x + 5y = 100 and 8x + 8y = 112
Subtracting 8x + 5y = 100 from 8x + 8y = 112
8x - 8x + 8y - 5y = 112 - 100
3y = 12
y = $4
Put in the equation 8x + 5y = 100 .
8x + 5 × 4 = 100
8x + 20 = 100
8x = 100 - 20
8x = 80
x = $10
Therefore the cost of one rose bushes be $10 and the cost of shrubs $4.