First off... let's use the decimal format for the percentages, so 85% is 85/100 or 0.85 and 45% is 45/100 or 0.45 and so on
let's say the quantities of each are "a" and "b" respectively
how much salt concentration in A? well, 0.45, so for a quantity "a", that'd be 0.45a
how much satl concentration in B? well 0.85, so for a quantity "b", that'd be 0.85b
now, she wants a mixture of 160ounces with 70% concentration, or 0.7
so the mixture will have a concentration amount of salt of 160 * 0.7
solve for "a", to see how much of the 45% solution will be needed.
what about "b"? well, b = 160 - a
let's say the quantities of each are "a" and "b" respectively
how much salt concentration in A? well, 0.45, so for a quantity "a", that'd be 0.45a
how much satl concentration in B? well 0.85, so for a quantity "b", that'd be 0.85b
now, she wants a mixture of 160ounces with 70% concentration, or 0.7
so the mixture will have a concentration amount of salt of 160 * 0.7
solve for "a", to see how much of the 45% solution will be needed.
what about "b"? well, b = 160 - a