How many militers each of a 40% solution and a 10% solution are needed to make 200ml of a 20% solution?
f = ml 40% , t = ml 10%
f + t = 200 ml
.4 f + .1 t = .2 * 200 ml
solve the system for f and t
f + t = 200 ml
.4 f + .1 t = .2 * 200 ml
solve the system for f and t