Instead of doing your homework for you, I'll do a different problem exactly like
yours step-by-step which you can use as a model to do yours by.
A certain alloy is 26% copper, 46% zinc and 28% iron. By adding 40 grams of zinc
to it, the new alloy now is 55% zinc. How many grams of each metal is in the
(ORIGINAL) alloy?
Let x = the total number of grams of ORIGINAL alloy.
Then
0.26x = the number of grams of copper.
0.46x = the number of grams of zinc.
0.28x = the number of grams of iron.
We start with 0.46x grams of zinc and add 40 grams of zinc to that. That gives
us 0.46x + 40. That increases the amount from x grams to x+40 grams. So adding
that zinc caused there to now be 55% of that increased amount of x+40.
0.46x + 40 = 0.55(x+40)
We can remove the decimals by multiplying through by 100.
46x + 4000 = 55(x+40)
46x + 4000 = 55x + 2200
-9x = -1800
x = -1800/(-9)
x = 200
So the amount of original alloy was 200 grams. So
0.26x = the number of grams of copper = 0.26(200) = 52 grams
0.46x = the number of grams of zinc = 0.46(200) = 92 grams
0.28x = the number of grams of iron = 0.28(200) = 56 grams
Now do yours exactly the same way, step-by-step.
Edwin