Answer:
640 = .8j
640 = 1.15c
Step-by-step explanation:
Let j = cost of Jocelyn's computer
c = cost of Corbin's computer
We know that Adrian's computer costs $640.
Since Adrian's computer costs 20% less than Jocelyn's computer, the cost of Adrian's computer is 80% of (.8 times)the cost of Jocelyn's computer, so 640 = .8j
Since Adrian's computer costs 15% more than Corbin's computer, the cost of Adrian's computer is 115% of (1.15 times) the cost of Corbin's computer, so 640 = 1.15c
