The scale factor for area is the square of the scale factor for linear dimensions. If linear dimensions are scaled up by a factor of 10, the area is scaled up by a factor of 10² = 100.
The area of the larger box is 100×432 cm² = 43,200 cm².
They both have the same denominator or bottom half of the fraction so you need to compare the numerators. 6 is more than 4 so Martin bought more fruit than Jack. Hope this helps.