I have 70% solution of saline solution and some 80% solution of saline. I need to combine the two solutions to get 8.5 ml of a 78% solution of saline

Question

show formula

Answer 1

(x ml)(70%) + (8.5 - x ml)(80%) = (8.5 ml)(78%)

70x + 680 - 80x = 663

-10x = -17

x = 1.7 mls of 70%

plus 6.8 ml of 80%