Question 939053
  
Method 1:  Using unknown x
step 1.
using unknown x=volume of 10% (=0.1) solution in ounces
then volume of 2% (=0.02) solution is 112-x ounces to make 112 ounces of 7.9% (0.079) solution.
  
step 2.
form the equation that mixes the two ingredients to make a 7.9% solution
0.1x+0.02(112-x) = 0.079(112)
  
step 3.
Solve for x
0.1x+2.24-0.02x = 8.848
0.08x=6.608
x=82.6
Volume of 2% solution = 112-82.6=29.4 ounces
Answer: 82.6 ounces of 10% solution, and 29.4 ounces of 2% solution.
  
method 2: using proportions
V(10%):V(2%)=(7.9-2) : (10-7.9)
=5.9 : 2.1
Volume of 10% solution = {{{112(5.9/(5.9+2.1))=82.6}}} ounces
Volume of 2% solution = {{{112(2.1/(5.9+2.1))=29.4}}} ounces
Answer: 82.6 ounces of 10% solution, and 29.4 ounces of 2% solution.