since this is a multiplication, all the numerators are just factors of the product numerator and all denominators are just factors of the product denominator, so we can simply reorder them some, without changing the product.
[tex] \bf \cfrac{7}{8}\times \cfrac{4}{15}\times \cfrac{3}{7}\implies \cfrac{7}{7}\times \cfrac{4}{8}\times \cfrac{3}{15}\implies \cfrac{1}{1}\times \cfrac{1}{2}\times \cfrac{1}{5}\implies \cfrac{1\cdot 1\cdot 1}{1\cdot 2\cdot 5}\implies \cfrac{1}{10} [/tex]
