Algebra Question!

Question

One fish tank has %4 salt mixed in. Another tank has 10% salt. A certain type of fish requires a 100-gallon tank which is 6% salinity. How much from each tank should be used to acquire the correct mixture for this species of fish?

Answer 1

.10(x) + .04(100-x) = .06(100)

.1(x) -.04x = 6-4 =2

.06x = 2

x =2/.06 =200/6 = 33 1/3 gallons of 10%

100-x = 66 2/3 gallons of 4%

4 is closer to 6 than 10 is, so you know you need more of 4%

4 is within 2 of 6, 10 is within 4 of 6

4 is twice as close. You need twice as much of 4% as 10%

66 2/3 is twice 33 1/3