Question 267037
this is a mixture problem. Here is a table based on given information.
solutions . . . . . . . % . . . . . . . . ounces . . . . . . %ounces
40 . . . . . . . . . . . .40 . . . . . . . . . .x . . . . . . . . . . .40x
45 . . . . . . . . . . . .45 . . . . . . . . . .12 . . . . . . . . . .540
mixture . . . . . . . .42 . . . . . . . . . .x + 12. . . . . . .42x + 504
looking at the third column, we get
(i) {{{40x + 540 = 42x + 504}}}
subtract 40x and then subtract 504 to get
(ii) {{{2x = 36}}}
divide to get
 (iii) {{{x = 18}}}