SOLUTION: James bought a packet of flour to make cakes. He used an equal amount of flour for each cake. After he had used the flour to make 3 cakes, 3/4 of the packet of flour was left. He w

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Question 1203847: James bought a packet of flour to make cakes. He used an equal amount of flour for each cake. After he had used the flour to make 3 cakes, 3/4 of the packet of flour was left. He went on to bake another 5 cakes and had 1400 g of the flour left. How much flour was used for each cake?
If you want to try to solve this problem in "words" rather than forming and solving equations then you could adopt this approach:-
After James had made 3 cakes there was 3/4 of the packet of flour left. This means that he must have used 1/4 of the packet to make those 3 cakes (4/4 - 3/4 = 1/4) and, therefore, he is using 1/12 of the packet for each cake (1/4 divided by 3).
(NB: 4/4 and 12/12 are both ways to represent the whole packet flour; you do see that don't you?)
Therefore, after he has made another 5 cakes (3 + 5 = 8 cakes in total) he will have used 8/12 of the packet of flour (8 × 1/12 = 8/12).
This means that he has 4/12 of the packet left (12/12 - 8/12 = 4/12).
So the 1,400 g of flour that remain after he has baked his 8 cakes is actually 4/12 (or 1/3) of the whole packet.
Can you now work out how much flour James was using to make each cake?
(Hint: He now has enough left (4/12) to make another four cakes, doesn't he?)

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

let amount of flour be x
if he had used the flour to make 3 cakes, and 3%2F4 of the packet of flour was left
%281%2F4%29x was used the flour to make 3 cakes and
%283%2F4%29x was left
He went on to bake another 5+cakes and had 1400g of the flour left.
if %281%2F4%29x was used the flour to make 3 cakes , then %281%2F4%29x%2F3=%281%2F12%29x was used for one cake
so, for 5+ cakes he will use %285%2F12%29x
x-%28x%2F4%2B5x%2F12%29=1400g
x%2F3=1400g
x=3%2A1400g
x=4200g

so,
%281%2F4%294200g=highlight%281050g%29 was used the flour to make highlight%283%29 cakes
%285%2F12%294200g=highlight%281750g%29 was used the flour to make highlight%285%29 cakes
and
1400g of the flour left

check:
1050g%2B1750g%2B1400g=4200g
4200g=4200g