So 200 mL of a 45% insecticide solution contains (200 mL)(45% insecticide) = 90 mL of insecticide.

Example 1: Salt Solutions

Solve.
Solution X is a 31% salt solution and Solution Y is a 25% salt solution. How much of each is needed to make 18 gallons of a 29% salt solution?
Solution X: gallons    Solution Y: gallons

	Amount of solution (gal)	% salt	Amount of salt (gal)
Solution X	x	0.31	0.31x
Solution Y	18 - x	0.25	0.25(18 - x)
Together	18	0.29	0.29(18)

0.31x + 0.25(18 - x)	=	0.29(18)
0.31x + 4.5 - 0.25x	=	5.22
0.06x	=	0.92
x	=	6

x = 6 gallons of Solution X and 18 - x = 12 gallons of Solution Y are needed to make 18 gallons of 29% acid solution.
Solution X: gallons    Solution Y: gallons

Example 2: Food

Solve.
How many pounds of lima beans worth $11.07/lb should be mixed with 49 pounds worth $8.91/lb to make a mixture worth $9.39/lb?
lb

Apply what you know about unit costs:   Amount of food × Unit price = Total cost of food

	Pounds	Price/lb	Total Cost
Lima beans	x	$11.07	$11.07x
Navy beans	49	$8.91	($8.91)(49)
Mixture	x + 49	$9.39	($9.39)(x + 49)

$11.07x + ($8.91)(49)	=	($9.39)(x + 49)
$11.07x + $436.59	=	$9.39x + $460.11
$1.68x	=	$23.52
x	=	14

x = 14 pounds of lima beans to add to the navy beans.   lb