A store experienced a 14.2% fall in takings in February, compared to the previous month.

Their takings in February were £742,513.20

How much did they take in January?

say the amount in jan is x we know if we subtract off 14.2% of x (from x) we get Feb's amount

so x - 0.142x = 742,513.20 (notice we change 14.2% to 14.2/100 - - that is what % is short for - - or, as a decimal 0.142)

we have 1x - 0.142x or (1-0.142) x on the left side

0.858 x = 742513.20

divide both sides by 0.858 to "solve for x"

x = 865,400