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

$x-\ all\ cakes\\\\ 50\%x=0,5x\\\\ \frac{1}{5}x=0,2x-\ fruit\ cakes\\\\ sponge\ cakes=1x-0,2x-0,5x=1x-0,7x=0,3x\\\\ Sponge\ cakes\ were\ 30\%\ of\ all\ cakes.$