+ + + + + +
4 is positive or + and so is 2
hope it helps
2p + 7p = 747
9p = 747 divded by 9 = 83
2 * 83 = 166 7 * 83 = 581
Hope it helps
We have 10 ml of 20% acid to which we need to add "x" milliliters of 100% acid to make 50% acid.
.20 * 10 + 1.00x = .50 * (10 +x)
in which "x" is the volume of the 100% acid to be added.
2 + x = 5 + .5 x
.5x = 3
x = 6 milliliters
Source:
http://www.1728.org/mixture.htm
Scroll down to problem B