How many mls of 45% dextrose and 15% dextrose do you need to make 780 mls of 35% dextrose

Answer 1

amount of 45% stuff --- x ml
amount of 15% stuff ---- 780-x mls

.45x + .15(780-x) = .35(780)
times 100 to get rid of decimals

45x + 15(780-x) = 35(780)
take over from here