Let X be the original price. Do a 40% increase we get the price: X+0.4X=1.4X Doing a 25% off we get the new price: (1.4X)-0.25(1.4X)=1.05X =X+0.05X. The new prices are 5% increase from the original price.
You would graph the two lines. Then use Y=mX+b 10=5/4(4)+b 5/4 is the slope or distance between the two lines. solve for b 10=5+b -5 5=b Y=5/4X+5 would be your answer