Question

50% of all the cakes Jenny baked that week were party cakes, 1/5 were fruit cakes and the remainder were sponge cakes what percentage of cakes were sponge cakes

Answer 1

1/5 = 20% so 50+20=70
100-70=30
so 30%

Answer 2

Answer:  30% of the cakes were sponge cakes.

Step-by-step explanation:  We are given that 50% of the cakes Jenny baked that week were party cakes, one-fifth were fruit cakes and the remainder were sponge cakes.

We are to find the percentage of cakes that were sponge cakes.

Let n represents the number of cakes that Jenny baked.

According to the given information, we have

$C_p=50\%\times n=\dfrac{50}{100}\times n=\dfrac{n}{2},\\\\\\C_f=\dfrac{1}{5}\times n=\dfrac{n}{5}.$

Therefore, the number of sponge cakes is given by

$C_s=n-C_p-C_f=n-\dfrac{n}{2}-\dfrac{n}{5}=\dfrac{10-5n-2n}{10}=\dfrac{3n}{10}.$

Therefore, the percentage of cakes that were sponge cakes is given by

$C_s\%=\dfrac{\frac{3n}{10}}{n}\times100\%=30\%.$

Thus, 30% of the cakes were sponge cakes.