Righto, lets get started.
The total amount spent is $922 and we know that this amount is made up of a certain number of hats at $19 each and 40 hats at $25 each.
Therefore we can say:
$922 = $25 x (pairs of shoes) + $19 x 40
Therefore, we rearrange the equation to find the number of shoes:
$922 - $760 = $25 x (number of shoes)
$162 = $25 x (number of shoes)
divide the remaining amount of money left over after purchase of hats by the cost of one hat which is $25
$162 / $25 = 6.48
Therefore we can say that 6 pairs of shoes were bought. We wouldn't say that 6.48 pairs of shoes were bought because you can't by 0.48 of a pair of shoes! So we round down in this case to the nearest whole number.
Hope that helps!!