If $10 can purchase 4 bunches of purple grapes, then how much can 25 purchase
Mathematically,
$10 is equivalent to 4 bunches
$25 is equivalent to x bunches since we don't know the number of bunches $25 can buy
10 dollars = 4 bunches
25 dollars = x bunches
The proportion is given below by introducing cross multiplication to the above expression
[tex]\frac{4\text{ bunches}}{10\text{ dollars}}\text{ = }\frac{x\text{ bunches}}{25\text{ dollars}}[/tex]