Assume n represents one notebook price and f represents one folder price.
1) n=f+0.75
2) 2n+2f=6.50
multiply equation (1) by -2 and add it to equation (2).
2f=-2f-1.50+6.50
4f=5 therefore f=$1.25 and two folders cost $2.50
One notebook costs: 1.25+0.75=$2.00
Two notebooks costs: $4.00
