How many unique solutions are there to the system of equations below? x+3y=7
-2x-6y=1

a zero
b one
c two
d infinite

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. amy spent $112 on 8 rose bushes and 8 shrubs. what is the cost of one rose bush and the cost of one shrub? rose bush: $15,shrub: $5. rose bush: $10 , shrub: $4. rose bush: $7 , shrub: $5. rose bush: $13 , shrub: $2. pls will mark brainliest