This is a mixture problem. I do these with 3 large boxes. First and second box are the things we are mixing. They have a + sign BETWEEN them. After the second box goes the equal sign, then the third box which is the result. Inside EACH box goes two numbers. One is the % and the other is the amount.
From the first sentence in the problem. 28% and 64% go into the first two boxes because these are what is being combined. The third box gets the 49% because it is the final result. This one must always be the number BETWEEN the other two %s.
Only one number left to deal with. That is the 49 pounds. It says "49 pounds containing 45%, so it goes into the box with the 45%.
We do not know the numbers in the other boxes. So make one of the x and the other y. Now we have two expressions in each of the boxes.
Now we can create two equations by reading across. Turn the %s into their decimals.
x + y = 49.
and
.28x + .64y = .45 (49)
Solve the first equation for y and substitute it into the second.
y = 49 - x. So
.28x + .64(49 - x) = .45 (49)
Solve for x, then solve for y.
